Child custody advice before filing for full

So my daughters dad is taking me to court for our daughter. He thinks he will get full custody. Well hes a convicted fellon, and spent a year and a half of her life in jail. For abusing me and pulling a gun on me at work, because i left him and started seeing someone else. I let them take her for two weeks like joint custody but not the court orderd way. I just thought be would change his ways pluss he lives with his mom who is good with my daughter so as long as she was around it was okay. Then he started callingall the shots. Saying shes going to school there and rather or not i could cut her hair. I had enough nd decided to keep her with me. So now hes taking me to court and saying im going to loose her. Ive never been in trouble. Have no record, and don't do drugs or smoke pot, or drink. Im getting married and i.have my own house with my fiance. We have our own vehicle and we both have good paying jobs. He works under the table, drives his mom's car, lives in her house. His family all does drugs and have been in an out of jail for years. Im not over exaggerating either. Is there a chance he will win because he is taking me to court? And does anyone have any advice for me