He doesn't want to sign away rights.

I am wanting to give my child up for adoption and found a great couple who is interested and wants to move forward with the process. I am 20 years old and have a 3 year old, and a 2 year old. I am 7 months pregnant and all my children have the same dad. He left us in May of 2009, moved 1200 miles away leaving me with the bills, ect..he came back, but after realizing it just wasnt the same and that I didnt want to work on our marriage anymore, I asked him to leave again and this time he is gone for good. So I filed for child support, havent messed with trying to get a divorce, I can't afford to even look into that right now. He hasn't sent ONE single penny since he has been gone and refuses to. He is very very childish, has mental issues (seriously) He is on probation for assault with a deadly weapon and burglary (he broke into my house to try to talk to me when i refused to answer the door to him..awhile back..) I never put a restraining order on him. He used to be phsycially abusive towards me and is still very disrespectful and verbally abusive towards me. He has a temper and I AM scared of him. He won't sign over his rights, however he does NOTHING to even try to help support his kids. He keeps telling me he is getting enjoyment out of seeing me struggle and have it hard since that is what i did to *him* when I made him leave (after he abandoned us..) I also know that he tried to commit suicide not to long ago which goes to show he is mentally unstable. In my opinion, he just isnt fit to be a parent at all.
I don't think he has the money to hire a lawyer to fight for his kid in court and even if he did I think he would lose anyway. I definately do not want the baby growing up anywhere close to his very unstable family. The thought of that scares me so bad. Anyhow, he lives in Florida and I live in Kansas. The potential adoptive parents live in Alaska. I really want this to all work out, any input or advice would be greatly appreciated.