Oh OP - haven’t read the whole thread but please dig deep and give everyone some grace.
You’re doing nothing by harbouring all this anger about ‘disrespect’ - you’re not an angry young man spoiling for a fight!
The ONLY way that this is going to move forward with love and light is for you to take the high road. Insisting on being ‘right’ and making your husband ‘take a stand’ is only
going to entrench you further is this.
Imagine that, instead of being angry - you sent a card saying ‘you totally understand not being involved in the day given the long history, but that you’re thinking of them with love and wishing them a life time of happiness’
Imagine your DP went, happily, with your blessing and had a lovely day celebrating his daughter and it was a place of healing and reconnection for them.
imagine you manage to put down your own hurt and anger and feel some compassion for the girl who is still conflicted and upset about her parents marriage ending and looking for somewhere to put those big feelings.
And imagine how much more room you’ll have if you let this all go. The no. 1 winner would be you.
book a spa day / go see a show with a friend / extend all your grace and compassion x 100 to yourself. Bless them and block them from taking up any more space that necessary in your head ever!