Im sorry, i know how tough it is. I know how difficult it is to even have him around.
Re his ap- there is literally nothing you can do about it, my h used to try and tell me about hoe lovely the ow was, i told Him point blank, im not interested, i do not want to meet her she doesnt exist in my life, keep your life away from me. You do not need to know Rachel, the less you know the better! At this stage i dont even know where my H lives.
Re kids- eventually depending on how much you h pushes he will have them at the new place and you will also be ok. Yesterday h took kids and ow out for the day, if it wasnt for his Words in the morning i was actually ok about it.