Hi there, and welcome.
It sounds very stressful for you, to deal with all those detoxes and rehabs, and I assume quite a bit of him drinking inbetween. Have you got any support during any of those times -- any family groups in counseling, or have you done any individual counseling or gone to Al-Anon?
I was married to an alcoholic for 20 years, and I found that I spent so much time worrying about him -- was he drunk? was he breathing? would he die? -- that I totally neglected myself. It wasn't until I started going to Al-Anon that I could even really admit that I wasn't happy in a relationship with a guy who was drunk every night.
As for what you can do about him choosing to take a relapse? Nothing. If he's chosen to drink again, he's chosen to drink again.
In Al-Anon, we talk about the three Cs: You didn't CAUSE his alcoholism; you can't CONTROL it; and you can't CURE it.
He's an adult and he is going to make decisions for himself. You can't control whether he drinks -- the only thing you can control is you and your reactions, attitudes, and choices.
If he's started drinking again, you'll find out soon enough. I think the question I would ask is -- what are you doing to take care of yourself in this situation?