This guy sounds like a freak. Seriously, get some help. Ask your parents to talk to his parents and make sure they reign him in. Let your teachers know what's going on. Do not let him get away with this.
Even if you had broken up with him in person, it wouldn't have helped things. And no, teenage hormones are no excuse for his behavior.
And to answer your questions...face and phone are the only proper ways to break up, and most breakups either end in tension or never speaking again. The post-breakup friendship is a myth. Avoid dating people who you're going to have to deal with if or when you break up.
Even if you had broken up with him in person, it wouldn't have helped things. And no, teenage hormones are no excuse for his behavior.
And to answer your questions...face and phone are the only proper ways to break up, and most breakups either end in tension or never speaking again. The post-breakup friendship is a myth. Avoid dating people who you're going to have to deal with if or when you break up.