BF “chose” drinking over me

Long story short; I’ve caught my bf sneaking alcohol multiple times. Each time, he lied to my face multiple times about it, I think he thinks I’m an idiot. He says he’s ashamed/embarrassed of the problem and that’s why he doesn’t tell me. He’s restarting therapy and trying to exercise more, and trying to stay sober. However the last time this happened, he started huge fights all night long with me, said awful things, and yelled at me. Drinking didn’t cause that per se but it released the inhibitions to do so, which it’s scary to think all that stuff existed deep down inside him. I’m also afraid that because he lied, I’m worried he could be lying about other things too; kind of opened up a can of worms. I want to support him through this because he’s struggled for a long time and it runs in his family, but if he’s not honest what can I do?