how do I support and validate without colluding?

[c0dependent]

Hi everyone, new here. My brother got his diagnosis about 6 years ago now and it felt like someone had turned a light on for me. It has been an incredibly rocky road since then with me trying to unlock my own codependency and with a lot of up and downs that I won't go into. My question is this. He's currently splitting on someone and has been for a few months. Every time I talk to him he rages and blames her for everything that has gone wrong in his life. This person cut contact with him after a really difficult year where he was often verbally cruel to her and she supported him through a lot. I have no interest in taking sides etc and I can really understand that he's incredibly hurt and that this rage and blame is part of an ego defence- but how do I validate his feelings without colluding? And is getting him to actually look at his behaviour and work to change it too much to hope for? 

[khibomsis]

  Codependent, and welcome to the family! I am sorry to hear about your brother's rage, it is always difficult for family and loved ones.
The bottom line is that there is not much you can do. Your brother needs to be in treatment for there to be hope of change. I take it you want to keep some sort of relationship with him? Then beware, because at some point you will be split black too.
It is a tricky situation. Obviously you cannot validate the invalid. If you feel he is acting wrongly, keep that to yourself. What you can do is validate his feelings of hurt and disappointment. "I am sorry you feel like that" is often heard as a stereotypical response, but it captures the sentiment you need to be expressing.
Here is a lesson on validation. https://bpdfamily.com/content/communication-skills-dont-be-invalidating
Let us know what you think will work in your situation?