I don't know if it was the right thing to do

I broke up with my boyfriend almost one year ago, but we kept hanging out acting as if we were on a relationship. I love how we are together but through this year I kept thinking about different reasons why I shouldn't be with him, I'm so confused, I don't know how I feel about him. There are days in which I feel I really want to be with him, and other days in which I'm very indifferent with him, I also need to come clean and say I like a guy I recently met at school.
In the last weeks I barely saw my ex boyfriend because we were busy with school and work, I thought there was no reason to have a relationship with someone I saw one or two days in a month, and that I should meet new people.
Yesterday I couldn't stand it anymore and I broke up with him for real. Now I feel terrible, I miss him so much and I don't know what's wrong with me. I honestly don't know how I feel about him. We had a beautiful 3 years relationship and I messed it up. I really love being with him, we have so much fun together, he treats me really nice, he loves me and I don't want to hurt him. But if I really love him, why do I have so many doubts? why do I like other guys?
I didn't want to get back with him and feel trapped in a relationship with so many doubts again and thats why I broke up with him, but I'm not sure that was the right thing to do.
Please don't judge me, I need an advice.

Advice on what? You did the right thing by breaking up with him. He was your ex so I'm not sure how you managed to break up with someone you weren't even committed to but that's neither here nor there. Point is, that you want to pursue other guys, your ex is an ex because you barely saw one another and right now you're just confused.

stop all contact with your ex once and for all and get on with letting that guy at school know, through your actions that you are interested in him.

You'll be fine, just keep busy, do lots of fun things with your friends and family so that your mind is off him and in no time at all, you'll find you no longer are missing him.

I would totally cut him off as best as you can. A lingering broken relationship will hold you back from enjoying yourself and meeting new people.

It is rarely a good idea to keep in such regular contact with an ex. From your own account, you were basically still pretty much together, you just officially considered yourselves no longer a couple. I know hindsight is always 20/20, so this advice comes too late, but that is really never a good idea. You either break-up and make a clean break or you don't break up at all.

If you broke up in the first place, it must have been for a reason. Unless the things that caused the break-up have changed, why would things be any different now? I mean, you should definitely think long and hard and do some soul searching. Is it true that the reasons for you breaking up in the first place were things that should not have broken up your relationship? Then maybe it would be worth it to see if you could work on it. The thing is, you remained officially broken up for a while even if you were still sort of unofficially together, so I kind of lean towards doubting that it would be a good idea to get back together.

In all likelihood, there is a pretty good chance that getting back together would just eventually lead to you feeling unhappy again. You don't deserve that, nor does he deserve to be with somebody who doesn't really want to be with him. So, take some time to yourself, heal up from the relationship, and learn and grow from the mistakes you may have made as well as those he may have made. If you don't learn from your past mistakes, you are just doomed to repeat them,

Good luck to you. Your soul mate is out there. It may not be him, but that doesn't mean he doesn't exist. If it isn't this fella, it just means you haven't found him yet.