Well, see what your attorney has to say. It sounds like you're going to terminate his right, and get full legal custody of your son, although you use other terms. Make sure your attorney explains what everything means. I worried too about what would happen to my children if I died when their dad was in prison. I had a will that requested my parents take them, and also gave my parents power of attorney so they could act on my children's behalf if something happened to me. I was advised that custody would automatically go to their dad, despite my will and POA. But, those documents would show the court my wishes. Also, for my parents to be granted custody, they would have to prove my ex unfit, which is not hard to do about a person who is in prison. So, while I knew there was some risk, I was fairly confident things would work out the way I wanted them to. And they did...my ex got out of prison, spent a few weekends with the kids, got another woman pregnant, moved far away and never ever paid support. We haven't seen him in over a year, and he calls about once a month. Based on that, his parental rights are being terminated and my new husband is adopting the kids. And my ex was someone who, from within the prison walls, said he thought of nothing but his kids! They'll say what they have to, but they don't have a leg to stand on. Don't let him get to you. You know what's best for your child, and the courts will agree that a man in prison for 10 years who has never know his child is no father.
Good luck. I'll pray for you.