Are you familiar with the work on self-compassion? (Kristen Neff and Chris Germer write and speak a lot about it). We are so much more willing to talk to ourselves in blaming, negative terms than we would ever say to another person! Two years ago I developed an autoimmune disorder, last year I was diagnosed with breast cancer. I, too, can fall in the hole of wondering what it is about me that is causing my body to develop these things. It can lead to a lot of “if only…” thinking. It’s just not helpful for me. I’ve gotten pretty good at noticing it, reminding myself that there is so much that is unknown, giving myself a small dose of self-comfort, and focusing on all that is fine and good right in front of me. You will get there! It’s a bit of a shock to become part of this (vast!) “club”. You need a minute to adjust. I hope your treatment goes as well as it can. Find doctors who listen and are willing to talk with you, if you can. And keep checking in if it helps.