How to divorce an abuser

I have been seperated for a long time now and I am a sigle mom of 2 wonderful children. He has been on the run from childsupport for years and was very abussive during our misserable marrage. I have recently located his where abouts in St. Lucie County Jail in Florida. He says he won’t sign for divorce and he knows I can’t afford it. I need help so that I can have a new beginning for me and my children. I will appriciate any help or information at all. Thank You!