Every situation must be handled according the merits of the individual case.
However, according to HaRav Dovid Cohen and other poskim:
*Children (even adult children)of abusive (sexual or physical)parents are exempt from communication. Based upon the effects of trauma caused to the individual by interaction. One need not receive a psychological diagnosis to determine their mental health is suffering due to the interaction.
*Children (even adult children)of verbally, or emotionally abusive parents are NOT exempt from communication, UNLESS they have a bonafide medical diagnosis. However, limitations should be worked out regarding the type and duration of interactions. There must be an exit strategy to avoid mental harm of the child.
*If a parent causes financial loss to a child, they are responsible for restitution. Kibbud Av does not give a free pass for parents to harm their children. Din Torah for financial loss are permitted.