Sorry to hear that you're in so much pain. I hope you feel free to pull out if it becomes too much.
XW went thru bone marrow donation ~2 yrs ago, and I remember the palpable press from the donation folks about seeing it thru, while I had a much more protective stance, focused on her well-being.
Be careful, Jo. You are a wonderful person and there are 4 little ones who really need their Mommy.