How do I explain it? (Sorry long post)

The past few years have been the worst of my life, when they should be the best. I changed my life for the better, made myself healthier, more attractive, more sociable, but always was overshadowed by the horrible things I've dealt with. I have hit my lowest point during this time, bordering on suicidal, even having thoughts of how things would be easier if I were dead. In September of 2012 my best friend died. We weren't on speaking terms, we'd had a falling out, and then, when he needed me, I wasn't there. In October of 2015, my sister died in the middle of the night. She was gone for no reason, and to be honest I didn't know if I could take much more. The absolute agony I was in constantly lasted for months, and seemed like it wouldn't end. I carried on with school, getting accepted to my sisters old university for grad school, and now every day was painful just knowing I was in the same place she use to be. I just found ways to survive, and I didn't even know if it was worth it. Then, in September, I met this girl. She talked to me first, that's why I knew it was something different. That never happens to me, ever. We met at the dog park, she wanted to meet up again so our dogs could play. For months we kept this up, eventually I started messaging her about other stuff and we became friends. We were both insanely busy and didn't have time to do much else, but we wanted to get together. But, I could already tell I was into this girl. She...made me happier, made the anger and hate I had for the entire world go away for a little while. We finally got to hang out a few times, I learned some about her, I was hooked. But there was a catch. She was fresh out of a relationship, a very serious one, and a very long one. I thought to myself then that the last thing she needs is some amateur like me to be trying to start something with her. I felt like what she needed the most right now was a friend, and to be honest, so did I. So, I didn't really push the issue past being friends. But, there were a few instances where I thought for sure she was into me, and something would happen naturally, but never did. The truth is, I think this girl saved my life. I was so far down, was so full of anger, misery, and pure hatred for everything. I had so much taken from me, and I know my situation isn't nearly as bad as it could be, but we all respond differently I guess. I was so close to the point where I wanted nothing anymore, but to just die. But she was there, whenever I felt bad, I would text her, or she would randomly send me funny instagram things, etc. and I was helping her deal with stuff, she confided in me, and me in her. She honestly was, and is, my best friend in the whole world. But, I think I love her now. I'm terrified of that, but excited by it too. But, I think I waited to long. I went away for the summer for an internship, and we got together with some friends when I got back. That was when they accidentally told me about this other guy she'd been talking to, and honestly I felt like I was gonna be sick. I blew it, whatever chance I could've had, I became the good friend, when I want to be so much more than that. This girl deserves everything, and I want to give it to her. I don't know if she wants this too, I don't know if she's ever even thought about it, or if she's just flirty in general. Now, she's moving away, and I can't stand it. She's not going far, but it feels like she's leaving forever. She doesn't text me as much anymore, or send me things, or confide in me, like she use to. I think it's because of this new guy, or maybe I just fell out of her graces. But I'm hurting so bad right now. I would settle for being friend with her if that's what it has to be, I just can't lose her completely. She may never understand how important she is to me, what she means to me, and what I would do for her, and that's ok. I don't want to scare her off, I don't want to creep her out, but, at this point I think maybe she should know about this? I've been going over and over in my head about how to tell her, what to say, how to make it feel like I'm not trying to coerce her into anything. I just want her to know what I feel, and I want me to be a man and say something for once, I'm tired of being the nice guy who stays quiet and finishes last. I just...don't know what to do, I almost feel like I should be ashamed of this. I love her and we haven't even 'dated'. She's just this amazing person, she makes me laugh and brings me out of the dark. I can feel my entire outlook on life rising up over the last year since I met her. But...these last 3 weeks since I found out about the other guy...I feel it all slipping, I feel that anger and hatred coming back, I feel that hopelessness. I know that's weak, I know that's pathetic, but that's just who I am now, I've taken as much as I can, I can't lose anymore and keep going. But I don't want her to be forced into loving me either, I feel like if I tell her all this, she'll feel obligated to be with me, to save me. I don't want that, I want her to be happy for reasons that she actually wants, and if that's with me, or someone else, I want it to be guiltless. My head is just so messed up, I thought maybe putting this down somewhere would help. I don't know what to do, she's gone soon, if I'm going to do something, it needs to be before then.

You need to try to have dinner (preferred) or lunch to catch back up with her soon. You will get a lot out of it in my opinion.

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I think what happened is that she has moved on since she thought you were not interested. Maybe I'm jumping the gun here, but did you talk about relationships before you moved away for the internship?

From my experience, women at her current age is looking more for a person to marry in a couple years than just a "friend." It's something with their biological clock. Lol!

First off. I'm sorry for the pain you've endured, you're a very strong person. You've been through a lot.
You will find overtime that will these were terrible,terrible things, you will gain strength as a result of it.
Male strength grows through struggle and hardships.

Secondly. I will do my best to give you some no BS advice, as this will do you best.

Well, never hold back, that's a problem. There's nothing wrong with you viewing her as important or special. Speaking your truth is important.
There's a right way to say it, and a bad way. The bad way shows desperation, that you can't live without her, that you need her, and you have self doubt.
The right way, shows that you want her, you value her, and are attracted to her. You're confident but not arrogant.
The problem was you weren't honest with your intentions, and you had self doubt. You should have gone for what YOU wanted. And have been direct and decisive.

A mistake was you assumed since she was out of a longterm relationship she wouldn't be ready for a new one. False, dont assume things like this.
And even if she wasnt, that doesn't mean you can't be romantic partners while she figures things out.

Other issues, you're placing her as a source of happiness. Which I agree, women make us feel great but we need to be able to sustain ourselves.
"I was so close to the point where I wanted nothing anymore, but to just die"
What happens if one day the relationship ended? What if she mistreats you? You need to get yourself together for your lovers.
It goes back to that saying, "I'll take care of me for you, while you take care of you for me"
Of course we reassure each other, and care for each other,but we need some self sustainability. Or else relationships just become landmines, and you will find that insecure people, while they'll get temporary satisfaction from relationships, they will eventually look for unnecessary faults and reasons to be sad, sabotage things, or end things.

I don't think you need to vomit up your feelings, but you need to make your intentions clear. She's with another man now? But he isn't her boyfriend?

I would make your intentions clear. Shoot her a message, say, "hey, back from my internship, I was thinking we should catch up over drinks sometime" whatever, dome thing along those lines.

Keep in m8nd that by leaving the friendzoned. You risk losing this woman in your life, however, its clear that you can't handle just being her friend as eventually you will lose her to another man that is direct and decisive regardless.

Don't be friends if you can't accept only friendship. As this will likely be your permanent fate in those situations.
Instead, state what you want, and walk away. Something along the lines of,
"I have to be honest with myself. I can't be just your friend, its painful to just be in a platonic situation with you when I have romantic feelings for you. I would really like to see where things could go. Let me know if you ever feel the same. I would love to take you out sometime"

Then, you walk and never look back, as it may be over forever. But if she gas romantic feelings for you, eventually she'll contact you.
Men are direct, assertive, and confident. Notice how what I said speaks the truth, and it's straight to the point. I'm also willing to walk away, not spitefully, but because I need to keep searching for that same feeling elsewhere if i can't get it here.