Have you ever been betrayed by a family member, extended family or not?

My father cheated on my mother MANY times during their twenty year marriage. This, the whole family knew. My father’s sister was on my mom’s side during the divorce and offered support emotionally as well as financially. Now, five years later, and a year of failing to pay court ordered child support and alimony, my father has decided to take my mother to court to try to get out of paying alimony. The catch is, my uncle (father’s sister’s husband who is obviously a lawyer) has decided to represent my father!
Has anyone been in this type of situation? If so, how did you deal with it?