Hi Giggy,
Welcome to the Parenting Board. So sorry to learn that your son isn't well and that your relationship with him is suffering too.
Not wanting to be party to a lawsuit is understandable. Have you been able to validate his feelings that he has been wronged in some way?
Our kids struggle with victim mentality and need an emotional supporter more than anything else from us.
Here is some info on Validation to help you get started learning about how and why it is so helpful to our kids:
https://bpdfamily.com/parenting/03.htmlbj