I'm one of those who gave my exAH many chances because I believed in him and thought he was going to change "this time". He went to prison for 2 years too. Did well for about the first 3 months after he got out, then picked back up and spiraled out of control within 3-4 months and we separated. When they pick back up, they can be just as bad as the last time they were using within a short time.
I share this, so you can have firm boundaries in place to protect YOU when he gets out. Like this boundary... I cannot live with active addiction... if you use, you have to leave. and maybe ... I cannot live in a house with violent behavior... if you do, you will have to leave. (I had to have the police come.. but I enforced my boundary.) And other boundaries that will protect your sanity and well being. Make a list.
Hopefully, he has found recovery and will continue to work his recovery when he gets out by going to meetings, not hanging out with old friends, etc. In time, you will be able to tell by his ACTIONS, not his WORDS.
Continue to read all the sticky posts here, learn all you can about addiction and what you're dealing with. Go to Ala-non or Nar-Anon meetings to get support for YOU.