My ex is accusing me of being a "bad mother!"

My ex and I have an 8 year old daughter together. He was in drugs or in jail for the first five years of her life. Once he was released from prison, he barely had any contact with her until he found out that I had a man.

Flash forward, three years later and I'm still with the same man. I swear my ex is mad that there's another man in my daughter's life which is why, he makes disparaging remarks to her and me.

I have sole legal custody, I've had it for 6 years now and he's now, fighting for joint custody (again I swear its a control thing.) He's claiming that he's going to fight for sole custody because I'm an "unfit" mother. My daughter is overweight and has always been overweight, she doesn't eat much of anything but still, remains overweight. According to her doctor, she was born overweight and she's not super concerned about it.

He's also claiming that my 15 year old stepson "physically abuses" my daughter which, is completely untrue. I've asked him to stop putting my innocent child in the middle of our issues because she's only a child and has no reason to be involved in adult business.

He is relentless about being verbally abusive towards me and now, hes doing it to my daughter. Visits have been stopped until we go to court again because his step kids, show my daughter "naked pictures of men" on the internet, she shares a room with boys who are ages 11 and 7. She was told to care for her baby sister unsupervised and a whole list of other events.

What I dont get is how I'm the "bad parent" when, all I do is care for my kids?