How Do You Handle a Comorbidity?

I've hate T1D since I was ~3 years old and Celiac's Disease since I was ~5. I've gotten used to my lifestyle. Growing up, I never felt strongly about it. Eating gluten free and bolusing felt like second nature, probably because I was diagnosed so young and had no other point of reference.

Long story short, I've been testing positive for thyroid antibodies the last two times I've gotten blood work done. My thyroid function's still good and I don't have any symptoms, but I'm worried. I don't know how I'll handle a third autoimmune disease. I know that having one can lead to getting others, but come on. Three?

It's taken me so long to get to a place where I don't hold resentment towards myself and my body over my conditions. How will I get there again? How does anyone tolerate being newly diagnosed for a third time?