What children actually read at these events
Children are not evaluating whether their parents are friends. They are scanning for whether they are allowed to be happy. At a wedding, a graduation, a birthday party, a child is doing constant low-level surveillance: is Dad all right over there, is Mum going to cry, am I allowed to hug my stepmother in front of them. That vigilance is exhausting, and it is the main cost of a tense relationship between adults — not the arguments the child never hears, but the ones she anticipates.
So the useful goal is not performance. It is permission. A child needs to see one parent say, without strain, "Go on, go and dance with them, I'm fine here." If you can give that line honestly, you have done the main job. If you cannot say it honestly yet, you can still say it kindly and then go and stand somewhere else for ten minutes.
How to get through a milestone you'd rather skip
Plan the logistics like you would a long-haul flight: where you will sit, who you will talk to, when you will leave, who is driving you home. Bring one ally who knows the situation and will stand with you in the awkward gaps. Decide in advance what you will say to the people who ask how you are feeling — one short, light sentence, repeated as often as needed, keeps you from improvising something you'll regret.
