A similar falling out happened with a spouse's relative who sent a hateful email saying that he wishes I was dead.
I have done nothing to him. He said that I and my husband were dead to him, entire family was losers, etc.
So I did not respond. He does not have any clue that I received it because I did not respond or tell anyone who communicates with him. So he is not in control. If someone hates you or says hateful things to you, that is their problem. It is not yours.
It's a construction of their mind and they are making themselves angry. It's not about you. Walk out. Leave. Do not tolerate it.
Disengage, relax, breathe, meditate. Think about other things. Go outside and look at the trees and the sky. You don't have time to waste on negative people. It has taken me years to learn that I have the absolute right to cut off anyone who calls me names or tells me I'm a bad person. I have the right to ruthlessly exclude negative people from my life for my own happiness. You do too.
You don't need to feel guilty. Rise above such negative thoughts that people are expressing towards you. I know it's hard to do.