Assalamu Alaikum,
Dear,
I have a cousin who behaive always bad with us. His father is my father's brother. He always jealous with us. He loves to spared rumor about my family and scold my father always. He has been doing this for a long time and my father forgave him many times. Now a days the situation Is getting worse. Can I cut all the relationship with him?

He scold your father? Why and how? Does he's got any issues with your family? In any case, this person insulting your father again and again and spreading lies about your family. Such person should not be allowed in your home. Yes, you cut all the relations with him. I will not let a person step inside my home who humiliate my family.

Are you asking for a lega, personal or religious perspective?

Do you live somewhere where you cannot bar people from your home or pick your friends?