Heartbreak sucks. It definitely does. How long ago did you guys break up? And have you had any contact with him since then? For me, personally, the best way to get over someone is to have absolutely zero contact with them. It's hard when you know you're still in love with them and you'd do anything to talk to them, but the best thing to do is realize that nothing is going to change. If it's been a long time, he's probably moved on. You said that he probably doesn't care about you anymore. Chances are he does if you were so in love with him, but the best thing to do is tell yourself that he doesn't want you anymore. The more you think that you might have a chance with him again, the more you're going to be continually hurt when things don't work out in your favor.
It sounds like you've been engaging in risky and unsatisfying behavior to try and "get over him." The best thing to do is to stop hooking up with random people, and reconnect with a few good friends who will support you. Try to find someone who genuinely likes you and respects you, and once you find someone else/stop dating people to try and replace him, I think it'll be easier for you to move past this. Good luck.
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when i play doctor, i play to win