Bea, I'm hoping and praying that your xh will act like a civil human being and keep his antics at bay during your son's wedding.
I do understand how you feel, especially after all of this time. For whatever reason, they can't cut the tie that bound them to us long ago. It's really a shame that he can't ride off into the sunset and touch base w/his sons periodically.
Take care.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.