Unable to understand why and unable to move on

I've been friends with a girl for the last six years who i had feelings for. She has come and gone in my life, usually when she had a boyfriend they would take priority. All through those years she has said that something could happen but it never did. At the time I thought it was just a matter of time. Now I realise that I was just being stupid. She has two boys that I grew really close too. Anyway recently we had a heart to heart after having a drink and she said she thought we were destined to be together and that she wants me to be the man her kids look up to. We hooked up that night. The week after she was just silent. I finally got her to talk to me and she said it's best we don't see each other again and that she couldn't remember what she said. That was a few months ago. I've just saw she is with someone new. I'm gutted. Im so confused why she would treat me how she did and if she ever meant anything she said. And If she didn't why say it all in the first place. I've tried dating but I haven't got the heart for it, I can't see anyone in the way I saw her and I've just stopped pursuing anything because of it. I'm miserable and I'm not sure what to do. It's obvious I'm not going to get closure from her. Also adding in that I miss her two kids like crazy it's just an awful situation. I gave no right to feel this upset as we were never together and her kids aren't mine. So I'm just left how I feel now which is confused and alone. Any similar stories or advice would be good thanks.

just move on. chalk it up to lessons learned and let it go (one of the best skills we can ever learn is to "let it go").
We aren't always going to get closure.. we aren't always going to get all the info.. we aren't alwyas going to get our answers. that's life. Learn how to let go and provide your own closure.

the most important thing is to move on and realize that the only person you can eer trust and that has your back 100% of the time - IS YOURSELF. It's hard enough surviving thru this world having to worry about anybody else and so most people focus on themselves.

Someday you WILL get your answers and undersatnd. I promise that. But right now you just need to move on and accept that 1) its over, 2) she's not a positive in your life and you need to let her go, 3) its probably never going to chnage, 4) your best move is to just move on period.

good luck.

so you have been good friends all those years
then you finally have sex
and after that she gets out of there. Did i summarize this correctly?

if i did - then maybe the sex and how you treated her apart from that perhaps just wasnt any good. Most women also seek some domination and initiative - which you completely lack obviously.

Im only guessing but id give myself a 70% chance that i am correct with all three things (bad sex, missing domination and initiative)