You need to find better guys to be with, these two are clearly fucked. I know when people are stressed out about this people tend to make bad relationship decisions, or date people who treat them like shit because they think they can't get better, but trust me hun, there is better, there's respectful guys who won't get drunk and abuse you, or stalk you after a break up, and they aren't at all difficult to find.

I may be being quick to judge, and this yelling incident with your boyfriend might be a one-off thing, but it sounds pretty fucked to me, and I think you have to get out of there.

I can't keep putting myself in this position.

Exactly, but don't blame yourself too much, people can feel like it's the only option and feel trapped, abusive relationships is all they know, so they continue to accept abuse as the norm which is unhealthy.

What you did with the whole head shaking ordeal was bad, but don't to be expected if his stalking is severe and causing you stress, thus also causing irrational decisions.

My best advice to you is to cut these toxic people out of your life, find a boyfriend who doesn't mock you when you cry and get mean-drunk, avoid this stalker at all costs, get a restraining order if it's very severe, or if it's not but still a stress, and he's reasonable to an extent just talk it out with him and be straightforward and clear you want nothing to do with him.

You won't die alone, but you will be unhappy if you continue to associate with toxic people.

If you're scared of your ex or your current boyfriends, be sure to search for women shelters in your area or tell any trusted friends or family of the situation. There are good people out there who will give you the respect you deserve.

Don't hate yourself, because there's nothing to hate, these types have just been making you feel negative for too long and you need to get out of there.