Should I apologize, or should he?

It sounds like you've had a very rough few months here. I've read your question twice to make sure I understood all that's been going on. This is a relationship that began in high school and by the looks of things has ended as a total train wreck. I hate to say it but due to your ages I don't expect him to ever want to get back together with you. You can see if you look how much you've matured as a person in the last year and this is still going on. As is often the case girls seem to mature faster than guys at your age. Your going back and apologizing to him won't help in the least. If anything it will simply drive him farther away.