need advice

I need advice of anybody out there. I had two kids by a man that is now no longer in my life. I have taken him for child support but he refuses to pay. This man has taken me for everything so I am starting from nothing trying to raise two kids on my own. I have tryed to get help from the state to try to get this man cause flat out he is a dead beat. I have a friend in my life that wants to there father, and he does so much more for them. My son is terrified of his biological father that is also why at this point even if he tried I would not want unsupervised visitation rights. Anyway, my whole point in writing on this is this new man wants to adopt my children, and my kids love him and want him to be there father. I guess my problem is the natural father trys to play as a ghost, he gives false names and doesn't have a solid living address cause he is always moving around so It is very hard to find him. My friends say not to let this man adopt my children but only I can and want my children to be happy but to have the birth father sign over paterental rights I have to find him and that is something that I have not been able to do in two years. Can anybody out there please tell me if there is another way I can go about this? Cause I am tired of having to do this struggle by myself and having to stay in this state when I have better oportunities in another state, but because of this man I have to remain in this state with my children.