Just a topic I heard and got me thinking? If you were in this situation what would you do?

So the story was

My child’s is 5 & his mum wants to do a party and invite both her family and her boyfriends my wife’s family & my family? None of the family’s get on the only time we cross and speak is picking up our son as I had to go to court and get time for him.so my son knows no different then this. My wife is due our baby around February 23 and the party she wants to throw is 2 weeks after her due date. So depending on the situation is what happens

The past is bad with my childs Mum. When he was little he fell out of a upstairs window and she didn’t realise. As she was in another room. The week after this he ran away and I found him in the middle of the road. She buys no clothes for him he always comes in old clothes that are to small for him. She admitted that she doesn’t watch him in the street when walking to the shop and he’s nearly been hit by cars. He also ran into a bin and she laughed as he split his head open. He’s meant to wear glasses all the time yet she never puts them on him. He doesn’t have a bath for 3/4 days at a time.

So question is what would you do about the party? As we had plans to throw our own little family party as this is what we do every year and then we go to a zoo of his choice. ?