I have two children, 7 and 13 and have been separated for 7 years. Up until 12 months ago he was actively involved with them for 4 years and our Co parenting relationship was brilliant. He would attend everything school related, call them a few times per week when he didn't see them and consistent in the time he spent with them.
12 months ago he slit up from his girlfriend. Our kids liked her and they slept over on his weekends. There was talk of moving in together and my kids seemed ok with this .My ex was continuing to be involved actively and Co parenting was great. A week or so after this he changed, he was with a new gf. Since this time he has not had them some weekends because he has 'forgot' and other reasons. He has stopped attending everything and no longer makes any contact with the kids in-between seeing them in person.
My kids met my exs new girlfriend in October, they have met her 3 times. He has sold his house and told the kids he is moving in with her. My daughter is anxious, fretting as she does not know her, she has a 5 Yr old she does not know and is worrying about getting to school/seeing her friends because it's further away. I messaged my ex and said the kids have told me he is moving and I asked if there was a plan for them to get to know his gf before this happened/ways I could support them with the change. He told me it's non of my business.
My daughter has been off since she came home from her dad's at weekend. Upset, anxious and angry towards me. We talked and she is worried about the move, she is upset he hasn't been to our sons parents evening tonight and has ignored her message when she asked if he was going to hers. She has told me she doesn't want to live with someone she doesn't know and is upset the move is happening soon and dad is also getting married. She never tells him how she feels and I don't as when he sees her he will confront her and she hates this.
My ex now very rarely speaks to me and is hostile, we haven't fallen out, no arguments etc, nothing has happened.
I feel like I'm not sure what to do. This is happening and although I'm not happy about it happening so soon for them I want to support them. Where do I start?