Well starting child support case against him does not mean that he has any right to take your daughter from you. I have been there as well and done that! Start the case against him and then write EVERYTHING down, I mean every phone call house visit and encounter you have with him or his family. He can hire a lawyer and request custody, however without abuse of some sort he is highly unlikely to get sole custody. He does have a chance of getting joint custody, but given the age of your child, most judges will find that right now it is best of the baby to remain with the mother full time with court appointed visitation for the father. I will say however the likelihood of him actually going through all that is very slim. He is most likely just saying this to you to scare you from filing a case against him. Dont be afraid of him...be a good mother to your daughter and get the help you deserve from her father.
I know how emotional things can get but take it from me, its mostly a mind game they play with you. If he really wanted your daughter than he wouldnt be the absentee father he is currently is!! Stand strong and do what you need to do to take care of that lil one!
Best of Luck - now go get that child support!!
I cannot answer for all of them, but my FIL is one of them. In his case, he loves what he does so much that I'm sure he'd do it even if he made no money at it. He loves the adversarial process and he LOVES to win. He is very good at getting into people's heads and twisting things around. This definitely did not make him a good parent, but it made him one heckuva good lawyer!