Helping a recovering “alcoholic”

Title is pretty straightforward, I’m 22 & my spouse is 21. He grew up around alcoholism. His entire family are alcoholics (I didn’t know this until a few months into the relationship). I mean, I know they don’t drink 24/7 but they do drink heavily when they do. They can go for days, or even weeks. They still work & stuff.

Anyway, I feel like his main problem is his mom. I feel like she is the bad influence. She drinks & drinks, then stresses him out. Then he’ll want a drink. Or she’d even encourage him to drink with her, have him supply the alcohol & stuff. Meanwhile, she’s being a hypocrite & telling me she hates when he drinks if you hate that he drinks then why support his habits?? She too is no good. She’ll blow her whole 1000$ pay checks on alcohol & whatever else. I had to keep our son away from her for 3 months because she drank while he was in her care. I don’t know if I want to give up our relationship entirely, we’ve been together for 4 years. The only time he’ll drink is when we get in a big argument & I give him the boot. Lol. When he’s home with us, he’s sober & great with me & our son. I love him sober. But how can I keep him sober? How can I help him?