So, I’ve never had a connection with another person like I have with this guy. We were never “official” but we were incredibly close. We’re both very jealous people, we both did silly things (nothing serious) just to get reactions out of each other, but it never really affected the relationship.
He treated me so well, too, I can’t explain how happy his presence made me. However, the other weekend he told me something really personal about his past. Something he’s never told anyone else, and instead of being a decent supportive person, I got upset about it (I was also 12/10 drunk at the time so I wasn’t being myself). I left the room because I didn’t know how to react to it. I’d been through something incredibly similar, and it triggered all these memories that I don’t want to think about anymore.
I came back about 10 minutes later and apologised, but didn’t explain why I acted the way I did. I thought everything was okay between us. but the next night I went to a friend’s house. and she took Snapchat, saying “come drink” and sent it to a few people, which I didn’t even know about. He got upset with me because she sent the Snapchat to his friends, but not him. And then he brought up what happened when he opened up to me and said how it broke his heart, and he’s just not in the right head space for a relationship.
He ended up calling me, and I explained why I reacted the way I did, but he still just wants to be my friend now, and it breaks my heart. I know I should have been there to support and talk with him, and I’m so angry at myself that I didn’t, but I just want to be able to prove to him how much I do care and didn’t mean to act the way I did. I said even though it sounds stupid, I hope things can be different in the future when we’re both in better head spaces, and he said that’s not stupid, we’ll see what happens.
Do you think it’s possible for things to eventually work between us? He’s said he’s never had a connection with someone else like this, either, so I really hope things can work out.
LemonVibe 
No one can know if it will work out between the two of you. You didn’t say what it was that he told you (and that’s fine, you want to respect his privacy), but that does kind of make a difference. If he bared your soul to you, sharing a very private secret and hoping that you would be supportive, but you acted otherwise, then that will absolutely break his trust in you.
As such, what you have to work on right now is to regain that trust. Build that connection back up. It will take time, and you’ll probably have to do it as his friend only. But that’s the only way you have to see if you two can possibly work out.
Having said that, given how you’ve described yourself and him, as well as your explanation of how you both react to things, I do wonder if you have a connection with him because the two of you are very similar, but you’re also similar in a way where you’re going to constantly be at odds with each other if you’re in a relationship.
If you’re both really jealous people, for instance, that really doesn’t bode well for being together. In that case, you’re better off being with someone who’s a bit more level-headed — someone who won’t fuel your jealousy with his own jealousy, but someone who can help you build your own trust and security, so that you’ll stop being jealous.
Just something to think about here — just because you have a connection to someone or share a lot of common qualities does NOT mean that you’ll be good in a relationship together.