Are you having GnRH to put you into the menopause?
I had it last year for months and I found it really played havoc with my head. Having compared my experiences of a chemical menopause to those of friends going through the natural one, it seems to be a kind of concentrated experience. I found it left me very woolly-headed and struggling emotionally.
When you add real pain to that, it becomes still more difficult to handle. There were times when I was taking full doses of cocodamol and ibuprofen together and still struggling (I didn't have endometriosis, but a complex case of menhorragia, fibroids and really bad anaemia). I don't think the pain of a thumb from texting really compares, and I'm amazed that anyone could argue that it did! Unfortunately, I think people often confuse chronic and acute pain in gynae cases, in a way that is not helpful to sufferers of the former. Yes, I am sure giving birth is considerably more painful than endometriosis, but it's an acute experience. You don't give birth every single day for five years solid, slowly losing all hope that your life will ever be 'normal' again!!
Finally, one factor that is often overlooked in these cases is that it can be a terribly long battle from symptoms to diagnosis, because for some reason that I cannot fathom, many doctors minimise gynae symptoms. Isn't the average time for an endometriosis diagnosis something absolutely crazy, like 7 YEARS? So many women are arriving at the treatment stage plain exhausted, traumatised, scared and suffering quite severe consequences in terms of declining quality of life.
So, to return to your question, YANBU to be mad at him for being insensitive, but do bear in mind the above factors that make you more liable to go to 11 in anger when the situation with him is really a 3!! (Anger when you are ill is a bit like lightning - there are often many complicated causes that contribute to a slow build up of charge, and the danger is that one minor thing draws it all down).
Can you do something to distract yourself from the pain psychologically? Very gently hobbling around sometimes helped me, as did watching entertaining B-movies. A friend swore by those detailed colouring books and crafting.
for you, and I hope the treatment works for you.