I’m really annoyed by my lifelong best friend

My best friend since childhood grew up extremely privileged. Rich home, stay at home mom that did everything for her kids, lavish vacations, best education, etc. So when we got into college, her mom started showing symptoms of mental illness. She ended up being diagnosed with BPD and has been medicated ever since. But unfortunately she still struggles. Things like sleeping all day, and saying random things and being very blunt. My friend is very sensitive and takes everything her mom says to heart. She still lives at home with her rent free despite us being 33 so they get under each other’s skin a lot. My friend is constantly complaining about her mom so a few years ago I encouraged to see a therapist to talk about it. She took my advice and got into counseling. But ever since, she has made it her entire personality. Every conversation we have is about her therapy. About her psychologist. About her anxiety. About her issues with her mom. About her medication for anxiety. It’s constant. Nonstop. When I change the topic, she will circle back to it being about her therapy or anxiety. It’s been years of things like this:

It’s just constant talk about her therapist and TikToks about mental health. I cannot hold a conversation with her about anything else anymore. This is my lifelong best friend and I’m so annoyed by her lately that I don’t even want to talk to her anymore. She’s also SO MEAN to her mother who is such a nice woman and does her fucking best. She blames her mom for her anxiety and calls her crazy because of her BPD, but then wants all the sympathy and acknowledgement for her anxiety. It’s so awful. 😭