My ex husband hasn’t been violent but his emotional abuse has gotten worse post divorce. He plays the victim and tries very hard to manipulate every situation to benefit him.
The first thing to be assured of is that schools have been dealing with this since schooling started and the fact they told you he is coming is great. This means they know it’s going to be difficult for you. Legally there isn’t anything they can do but trust me when I say, they know.
My experience has been that the staff at school have kept the children engaged in activities and away from parents because of this type of situation. Don’t expect this to necessarily be the case but don’t be surprised if a couple of teachers are there to support your child(ren). For me, the school has what I call the Dean of Discipline who is a 6’8” ex NFL American Football player (I’m in Texas USA at a parochial school and these people don’t put up with parents playing games). He is a big softie with the kids but can intimidate a parent just by standing over them. He is great with my ex husband. There is a member of staff or two like this on every school.
For you, remember the children pick up on your stress so stay calm. Remember the school is the children’s place and not the forum for parents to score points. Sports Day is all about the children and if he tries to start something stay that and walk away. Expect him to show up with a girlfriend. Expect her to be glaring at you and then talking to your ex followed by a snicker. That means you are getting to them.
Most importantly try to get there first and if you can volunteer so you are with the children and kept busy. I always volunteer when I can. The children always go over to their father and that’s a good thing. Ignore his games. Play the long game by being calm, steady and dependable. Children prefer the consistent parent in the long run. The parent that is always there for them and provides structure and routine.
It’s one day. It will be ok. Your daughter is going to be ok. Big hugs because it is hard and no, it hasn’t gotten easier.