If a father is slandering and lying about his son to the rest of his family thereby causing a lot of pain and anguish, what should the son do?
The son must tolerate and be patient and never counter his father or hurt his feelings. Whatever wrong done by any parent must be tolerated.
It is good to talk to your father either directly or indirectly to know the reasons of his attitude towards you. That might help decreasing the misunderstanding.
Wassalam.