I don't feel comfortable with my kid being around my ex's new girl

My child’s father and I split up a few months ago and things were very hard he wouldn’t work with me on anything only against me. He used to let me call my daughter every night to say goodnight or ask how her night was the days she was with him since I agreed to 50 50 custody with out court but than he stopped letting me call her etc. I have never refused any phone calls of his to her and still don’t he has recently got a girlfriend within the last month and decided that he’s too busy with “work” that he can’t do 50 50 anymore I’m fine with it because more time for me I just wish he wanted the same. Since he brought his girlfriend around my daughter last week and didn’t tell me until after she was around her even though we had an agreement to meet someone if they were going to be around our child this was last Thursday she met my daughter And has only been around her 2 times and last night I found out my daughter was going to sleep at this girls house where idk where it is or anything at all so he’s jumping into his hard what do you think I should do? I get I don’t have a say when she’s with dad but I’m not comfortable with my daughter sleeping at this girls house when she barely knows her she’s only 3 and what if she doesn’t feel comfortable to ask to go to the bathroom or something or since she has a big dog at home she plays with what if this girls dog doesn’t like that she can play with my dog comfortable and gets bit etc

That’s something you definitely need to talk to him about. You guys already talked about needing to meet the other person before you involved your child, & he ignored that. Maybe set up a day where you have extra time to stay for a few minutes to meet the girl. He may not understand it but he needs acknowledge your feelings and try to figure out a way to make things work. If it were reversed and it was you with a guy, I’m sure he’d have some things to say too. If he doesnt, then maybe think about going to court. It’s a very big thing when it comes to your child’s safety and if you don’t like someone then you don’t like them.