^ at my age I don't have much left^
You are only 71, you could have 20 years of life ahead of you, do you really want to spend it as a sad appendage, trailing behind your ungrateful children and needy EX husband?
Get some therapy and learn to make decisions based on your needs as well as those of your family. Learn to set boundaries, to have the strength to balance your needs against the needs of other people.
Your current life makes you unhappy, your family feel that your place is in the wrong, whatever you do. Isn't it time that you took control of your life rather than putting it in the hands of those, who no matter how close the relationship, do not seem to care about you?
As for tour ex, he is your ex, you have no responsibility for him or his care, especially as his desire to have you back in his life is for entirely selfish reasons.