My ex husband did 3 stints in jail, the first one before our marriage, the second 2 during our marriage ... & all 3 were for drink driving. First one was 7 months, second 4 months, last one 9 months. They were the only times he was in jail.
First time I did all the stuff cynical one listed above. Second time I never visited him & I stopped him having any contact with us after he was verbally abusive to my daughter on the telephone. Last time I visited him 3 times ... I was desperately looking for any little thing to hang on to so I could keep believing he would change. I guess I finally had enough recovery under my own belt to face the truth by then because I called it quits ... & then gave in & let him come back for one more try a month after he got out ... even though I knew he was drinking again!!???
You'll know if your man is serious or not by what he DOES while he's in there rather than what he SAYS. I wish I'd been recovered enough to have walked away the first time, when I could see quite clearly that my husband wasn't changing a thing. Instead, I frittered away 10 precious years of my life because I was strongly co-dependent & was choosing not to face reality at that point.
He still calls me every now & again ... to tell me he loved me & he misses me. He's still drinking & he knows it's killing him. I still miss him too sometimes, but not enough to continue sacrificing my life to our symbiotic disease - codependence & alcoholism.
I wish you the best whatever you decide to do.