STBXH drama. WWYD?

eturp

I found out H was cheating on me about 3 weeks ago. I filed papers and he has already been served. Right now I'm in school and so H watches DS those 2 nights. Additionally, I agreed to him coming over to our house (where I'm living with DS now) to do occasional overnights-and I would go stay at my mom's house on those nights. Tonight was his first overnight visit. He came over at 3:00 when I had to go to work. I got off at 6:00 and had planned on running an errand and meeting people for dinner at 7:00. Before dinner I just had this gut feeling that I needed to drive by the house and make sure everything was okay so I did. Well, turns out the girl he cheated on me with was at the house. I took a picture of her car, called my lawyer and called H to let him know she wasn't welcome there, especially since he didn't clear it with me. He claims she was just dropping off food for him and didn't come inside (I don't believe that for a second). H doesn't have permission (or a carseat even if he did have permission) from the divorce papers to leave the house with DS. However, he has known about this overnight for 2 weeks and could and should have prepared. I told him after tonight he would no longer be getting voluntary overnights (and since DS is still so young and BFed no court will give him overnights anyways). My lawyer said since no parenting plan is in place yet, I have every right to take those overnights away from him. I truly am trying to think of what is in DS's best interest (as much as I want nothing to do with H) but I'm starting to wonder, this is probably at least the tenth lie I've caught him in since this whole thing started and frankly I don't trust him around our son, so what IS in DS's best interest? Have any of you experienced something similar with your ex? Did it affect your custody agreement? When I told a friend of mine, she suggested getting a nanny cam so I would know exactly what's going on when H is with him (and who is there). If I caught him violating the agreement in some way (having people over, taking DS out of the house, etc.) what would I do then? Do I have any legal legs to stand on to fight for supervised visits only? Any advice is MUCH appreciated!