Tucdoc,
I would not remind him that his mother wanted this. He knows. He may think you are trying to bias him against her, interfere, and he may resent that and blame you down the road depending on how his relationship with his mother goes. Stay out of his relationship with his mom, let him form his own opinions.
If he’s like my kids part of his anger/disrespect may be because he sees the hypocrisy of adults telling him he has obligations and commitments when those adults have failed to fulfill or walked away from theirs. Why does she/you get to weild the authority as a father/mother when you aren’t fulfilling the obligations of a father/mother as he sees it.
- Keeping an intact home - Modeling a loving relationship etc.?
My son has asked me straight up why his mother can do what she’s done, then still expect to punish or weild authority over him.
Since the seperation/divorce I have never told my kids they have to do something because “I’m your father!” I first explain the whys of it, if they don’t cooperate then I tell them it’s because I’m their legal custodian, or because they will lose X privilege if they don’t. I never play the Dad card. I believe I lost that right when I couldn’t keep their home together.
BTW, there are a couple of recent threads where you may be able to lend some perspective and assistance.
ETA: Celebrate his birthday somehow. Have you tried indoor electric go-cart racing? If they have one near you it’s really fun and a great activity for just two or three of you. Big party would be expensive. He needs to know that you’ll never regret your marriage since it had to happen for him to happen. Let him and your other kids know the pain however great was worth it to have them.