Remember, this is a gift to your child, not to your former spouse. If you are unable to meet with your ex-spouse due to your feelings of anger or emotional stress, make an appointment with a mental health counselor or family therapist to resolve whatever conflicts are stopping you from being civil and polite. Remember that you cannot control your ex-spouse's behavior, but you can certainly set the tone for mature, adult behavior. Be a role model for your child on how to behave with dignity and self-restraint. Think of the wedding as a public event, and arrange your behavior to suit the event.
All adults are capable of professional behavior, appropriate to the occasion.
Ask your adult child for the name of their photographer and talk to them ahead of the event to arrange for multiple family photo groupings. With so many combinations of families today, it is not unusual for photographers to have requests for several combinations of photos for the various extended family members, such as his two parents and their families, a former stepparent and their family, or her divorced parents and their new families. Advise the photographer of any uncomfortable combinations of people to avoid any undue strain. A photographer can be cued to be politically correct. Ask your child for the names of the ushers and sit down with the ushers and the bride and groom to discuss the most comfortable seating arrangement for all concerned.