I've been drunk many times in life, and hung out with thousands of other drunk people.
Being drunk doesn't turn you into someone you're not. And it doesn't plant new ideas into your head. All it does it lower your inhibitions. It lets things come out of you that you normally keep inside.
For me I've done some WILD and risky sexual things when drunk. See I'm an extremely sexual person but I normally don't do these things because I'm worried for my safety, catching diseases and the social consequences. The urges to do these things, I normally keep under control, but I've let it out when drunk.
What I DON'T do when drunk is, things I have no hidden urge to do. I don't start eating broccoli. I don't start reading cheesy romance novels. I don't start abusing people.
What I gather about your boyfriend is several things:
He does think these awful things about you, but normally keeps it to himself because of the consequences of saying it.
He's got some built up resentment towards you.
He's the type of guy who feels better by lashing out at others. Like if he's stressed, lashing out at someone and hurting them releases his stress in a way. He's inhibited to do that normally, but when he drinks alcohol his inhibitions are lowered and he feels able to do that. It's probably something he fantasize about when he's sober but doesn't have the guts to do.
Alcohol doesn't make someone into a person they're not and doesn't plant ideas in someone's head.
It's hard to break up with someone you love, I totally understand how doing that would be harmful for you.
If you decide not to break up with him the one thing I would ask of you is this: don't go into denial about these facts you have just learned about him.
Don't say to yourself, "Oh this is just a fluke and it's not really him."
Go into it saying to yourself, "I've learned he thinks these things of me, and he also feels satisfaction by hurting people when he's stressed. But for my own reasons I have decided to give him another chance."
I think it would be less bad if you got back together with him WITHOUT denial. That way you can keep your eyes open and it won't be one of those situations where you are trapped in an awful situation for years and bring innocent children into it, all because you are in denial.