I have 3 children from a previous marriage they are 3, 5 & 7. My ex hasn't made an attempt to call or come see his kids in over a year, my husband now is wanting to adopt them to give them a normal life. My ex has been to jail for drugs an also has sexual assalt charges againest him on my oldest daughter. He only lives 10 minutes from the kids an passes our house everyday. I wanted to see about getting him for abandonment but his check does get garnished for child support. If he doesn't work an pay he goes back to jail. Just need to know what to do or who to talk to about my husband adopting them? The kids doesn't even ask about him they think that my husband now is there dad. Please help me get some answers.

First he has to be willing to allow your new husband to adopt them to sign away his rights, but if he is ordered to pay child support or go back to jail it may not be that simple and would have to go through the Judge for approval I would think.
It would not be abandonment but adoption.

Ok, abandonment is not a issue here, since of course he is paying, and in most areas it only relates to the being put in jail for not paying.

Some states allow for righs to be taken away for going to prison, and the sex assault. I would ASSUME you have a order of protection that does not allow him to see the children.

But you will need to get an attorney and file for adoption, perhaps he will just sign, if not, you could have a good case against him, but that is never 100 percent, always up to the judge

You need to consult a family lawyer in the town where you live. They can advise you on step parent adoptions and what the rules are in your state. They can also advise you on the likelihood of a judge granting the adoption while your ex is paying. I know that where I live in Michigan, I was told the judge would only allow my ex husband to relinquish his rights if my current husband was willing to adopt. Have you thought of asking your ex to sign the papers for the step parent adoption? Does he realize he will no longer pay support if he allows the adoption? That might just be enough of an incentive for him to go along with what you and your husband want.