Mother who needs advise?

My husband was caught cheating 5 months ago. I am currently pregnant with our 2nd child and he asked me & my 18month old to move out of our home so he can put it up for sale. instead he moved back in and takes his girlfriend there nightly. He has not helped financially since nor have i asked for help. Up until today we had a verbal agreement that he see our son 3-4 times a week with no over nights. We attempted mediation with court but I think it was more about our lawyers. When everything was said and done he has to pay child support now he wont talk to me or even let me know simple things about our son during switch offs like if he had dinner yet nor will his family. to them I am this evil person taken their son for all his money ($460 a month). I tried to explain to him it was state law I have nothing to do with it. Now that he has to pay child support he has requested overnights I allowed one which was hard because I know why he is doing it. Tonight is my sons 1st over night with him and he is going to leave him at his parents so he can be with his new found love. I asked if I can have him since he has plans but he said no its his time. I feel I should have been given the option before his parents as I would expect he would to. We did agree on joint custody but he wants to take me back to court for 50% of over nights to reduce his child support. All i want are my kids with me. He thinks I am jealous because he found love again. she has three kids from three different men and from what I was told she doesn't even have custody of them. I am more hurt than jealous because our kids will be the ones to suffer and all I wan t is what best for them.