How can I stop myself from making poor choices and hurting the one I love?

I've been in a relationship for over a year. He's cheated and lied. I heard he's married, but he says he's not. Everything is very up and down; there's no trust. Recently, he went on a trip, and I promised him I'd behave and not drink because when I drink, I drink too much, and I tend to make poor choices. This time, I made a huge mistake: I drank too much, and I cheated on him. I slept with another man for about five minutes before realizing what I was doing is wrong. I told him and he just got really rude. He called me names and threatened me. I feel bad as I do love him. We just have so many issues. I'm not a bad person, I've just made a lot of bad mistakes. It's unintentional, and I know right from wrong, but why do I still make the wrong choice?