In a bad divorce when one party alienates the children, can the child tell the alienated parent not to come to the wedding?

ב"ה Shalom This is a heartbreaking question and giving you a Halachic answer, in my opinion, unfortunately won't solve the insult or pain of not being invited to your own child's wedding. Many years ago, I was present when the former Chief Rabbi, Rav Avraham Shapira of blessed memory was asked, if it is violation of the commandment of honoring one's father and mother if a child does not a parent to the wedding. He said it was, but he did not leave at that and immediately suggested a way or reaching out to the child to solve this delicate and emotional issue. Therefore, I suggest consulting with a guidance counselor about how to go about this painful issue. May he guide you in a way that you should be fortunate enough that the verse "He shall reconcile parents with children and children with their parents.." (Malachi 3:24) shall be fulfilled. All the best