Divorces make normally happy events and gather a shit show sometimes. Wait until they start bringing their new bf/gf to things. You can’t win. Either someone is going to be uncomfortable (almost always including you), or you can have several separate Christmas, birthday, holiday parties and then deal with them being annoyed they didn’t get to see you “on Christmas” etc. And then once they get remarried and redivorced, you can add another layer to that dysfunctional onion.

Anyone who thinks divorce is only hard on young children is very wrong.

Sorry you are feeling the fall out OP. You didn’t do anything wrong and one of your parents will likely always be offended from here on out,

Your dad could have come up and spoken to you. You are not wrong here, he is.

You probably felt the need to apologise because that's how we are raised, if someone voices their hurt feelings you apologise but you weren't in the wrong and didn't do anything wrong.

If he was the one who cheated why would he expect your mom to make an effort with him, he sounds like a narcissist. Get ready for him to not contact you and then complain that you don't call him.

He was wrong not to come to you. Love your brother! Your father was lucky to have an invite

I dunno. My brother has a tough relationship with my mom. At his wedding he isolated her (table placement) didn’t acknowledge her ect. He is justified in his feelings- but don’t lure folks in (with an invite) & then treat them poorly.
If you invite someone to be your guest- you should be able to treat them as a guest. If you can’t- don’t extend the invitation.
Your father or anyone is entitled to their feelings. They don’t always have to be a narc.

Your dad is making the day about HIM , rather than his son. If he wanted to chat with you, he could have easily walked over to you. He sound selfish.

Your dad blaming you is emotional abuse and controlling.

You should have said, "you should have come over to talk to me". He is the father, he needs to take the initiative to repair his damages. He is too obtuse to do that though.

If you are unaware on how to manage a narcissist you should talk to a therapist to navigate this territory.

You must not be weak with a narcissist. His actions affected the family and he must live with the consequences, you can't erase consequences. You will not be a referee between him and your siblings. His relationship with them is a two way street and does not intersect with his relationship with you. Don't get in the middle of that.

OP, your father’s previous behavior shows he’s a narcissist. This is just another way for him to bring the focus onto himself. Tell him how you feel if that helps you to get over your anger, but don’t expect him to understand because narcissists are incapable of self-reflection. Go live your life and keep your emotional distance.