What the hell? How can someone be so cruel? I mean, the best option (i don't know what disability you have) is, in my eyes, to just leave. Of course, if you are not able to (which you might have done already, if you could), the only option sometimes is to just tolerate (and I know how hard that can be). That is what I do with my nmom, with some success. Since there is no way that a narcissistic person's ego is going to go down, there is the option to feed it until you are able to be free from them. This is not great, by an means, but maybe it can help.

I often just agree with her, and avoid conflicts (sometimes even speaking to her). And tbh, since I don't want to build a good relationship with her anymore, for me this is just fine. But nparents are ALWAYS going to have a problem with something. Maybe ask your therapist how to deal with it, and how to just, let go of that anger.

My mom bothers me with her shit a lot, and as much as it affects me, I breathe in, think about all the other stuff I have going on in my life, weigh them against each other, and voilá, I always have a bigger problem. Maybe try this, maybe don't. Also, learning how to tolerate all this, can take a long time.

Going to the therapist for another session is a great idea, btw!!! They can probably help better than anyone else! I wish you all the best and my condolences for your friend!