How much of a chance does the father of my kids have on getting visitation or custody?

I've lived in Fl for 2 plus yrs with my 3 and 2 year old children. I was forced to move here after the father of my kids throw me out of our apartment while I had 1 child and the other unborn in GA? I had no choice but to move in with my parents in Fl. Since then, I have been their sole provider. He has had multiple attempts of suicide, arrest and overall mentally unstable. I tried to allow him to see & provide for his kids since then but he's still remained inconsistant and an emotional mess. I fear letting my kids visit with him without my presence b/c of his previous actions. He just doesn't care about any one else. He is still married with 2 older kids and another child after my kids. He doesn't hold a job or a home longer than 6mnth to a year. I just want him to leave us alone.