Personally, I would find a joke like that extremely insensitive. I actually struggle with similar issues with my boyfriend's family. You're not alone, I promise. So far, the only things that I find help me are letting myself vent about it to someone that cares about me, such as my boyfriend, my mother, or even one or two close friends. After that, I try to let it go. Difficult, yes, but there's really not much else you can do about it. The biggest thing is to try not to let other people's negativity bring you down.

I would also agree that perhaps it is time to shop around for a new therapist. If you don't feel comfortable with them, then don't stay with them. I did that, and it really ruined my relationship with therapy overall.

If you need to vent some more, feel free to PM me.

Take care!