Grandparents Raising Children Support Group
This community is dedicated to grandparents who are the primary caregivers of their grandchildren. In cases where the parents are not willing or able to provide adequate care for their children, grandparents may take on the role of primary caregivers. Join the support group to find support, share your experience, and get advice from other members.
My first thought is to ask if he has recently been put on any new medications, or if the dosages have been adjusted. You'd didn't mention which health issues he has, but you may want to Google them and see if emotional changes are part of them.
Your courtship and marriage seems to have been good, and he was willing to help you with the grandchildren. This seems to be a sudden and unexpected change that's even blindsiding you!
I would definitely look into some medical reasons before giving up...