Has anyone else had issues with a new girlfriend ruining your co parenting relationship and pushing custody??

I’m so frustrated and aside from calling a lawyer Monday I’m not sure how to deal with this.

My ex husband and I have two kids together, we separated a few years back when the kids were 1 & 3 because of him being emotional and physically abusive. Obviously we haven’t had the best co parenting relationship but we try, we do our best to communicate and work together. He gets the kids every other weekend and occasionally there would be days when his work was slow and he’d pick them up from school and spend a fews hours with them. He’s had many girlfriends since the divorce and so far they have been relatively friendly, easy for the kids and I to be around, and respected our co parenting relationship. Well he cheated on and broke up with the last one and started dating a new one two weeks after. I could tell something changed because suddenly he become VERY pushy about school pick up but only specific days which is very out of character, they’ve always been random days in the past. Well as the weeks go on I come to find out he’s dating a school mom and her daughter is in my sons grade and it’s one of his good friends moms. After finding out I sat down with him to ask him to be careful going forward, not to rush and push the kids into the relationship or use the kids. That if this doesn’t work we have to deal with the drama at school, and with our friends group because she is a friends sister, dad lives in a whole different town so if it doesn’t work out he doesn’t have to deal with the after math. He promised they weren’t introducing the kids anytime soon… well he wanted to pick up our son on the Friday of his weekend, I agreed to let him and it turns out they picked up all of the kids together (except our daughter) and went back to her house. Before this happened my son had found out two days before about his dad and this women when her daughter ran up and told him his daddy was at her house kissing his mommy. After all of this my son struggled in school and got in trouble constantly for two weeks straight I was getting calls from the school for him fighting and having a bad attitude. I addressed all of this with his father and nothing changed. Well this Friday I let him know my daughters preschool was closed due to the flu and she was home so I could pick up our son and then bring both of the kids for drop of in the evening. He became very aggressive and told me I would not be picking him up because he was and after they had some things to do in town and he would come get our daughter later in day. I’ll be honest I didn’t respond well to being told I couldn’t get him, i tried to stay calm and professional and responding with a repeat of my first text saying his daughter and I will be picking him up and later when he’s done with his errands I could drop the kids off. From there he became confrontational demanding that it be set in stone every other Friday is his day. I reminded him that that wasn’t in the custody order because with his work schedule he never knows if he will be able to get time off to pick him up or not and legally he was in my custody until 5pm, and him getting the kids anytime outside of that is me working with him and trying to be fair. From there the only comment he made was “I thought we could co parent better than this.” This is all happening around the time I need to leave to pick up our son. I called him 7 times between 1:12 and 1:50, after his comment I typed above I asked him to please answer the phone, at this point I didn’t know who was picking up the child since I didn’t have a clear answer. He refused to answer and said he would only talk to me over text. So I loaded up my daughters and left for the school while still trying to call him. My drive is 20 minutes long and dad lives in the next town over. When I pull up he’s already there, and he and his gf are sitting in the truck. Finally it clicked that he didn’t want me to pick him up because he and his gf were picking up all of the kids today, with the exception of our daughter. He refused to get out or answer his phone and finally texted back he would get the kids at 5, implying he wasn’t walking in to get our son. Well when I walked in his girlfriend glared at me and rolled her eyes as she walked by. He showed up at 5 at our house, with her in the truck and left with the kids. My poor daughter has never even met her yet and the girlfriend stayed with them all weekend.

So his co workers wife and I are very good friends and after speaking to her I come to find he’s been telling this girl he has 50/50 custody just like her, and the days he was pushing so hard to pick up the kids were her custody days. He has visitation rights and every other weekend only. Problem is I think she’s pushing him to fight me for his “days” that he claims he has 50/50 and now it’s creating problems with our co parenting relationship, she’s gone as far as to have him block me on all social media, and my mother. She herself has blocked my husband and I (we knew her before and her brother and my husband are friends.) My ex has chosen to refuse to talk to me all together since so I can’t even communicate with him. I’m considering to stick strictly to the custody order, which doesn’t allow for school pick up and he would then only see the kids every other weeks on Friday at 5pm-Sunday at 6pm, until we can get back to communicating with each other. But as long as she’s pushing him I don’t know how that’s going to work.