I can kind of understand the ex's contacting him with words of support as he goes thru his treatments for leukemia. If you want to remain in the relationship with him, maybe you should accept that these women are just offering support during his illness. That said, do you want your precious time to be devoted as a caregiver? You have stated that he has family who can care for him. How much time do YOU have? Is this how you want to spend your time? When maybe you could be meeting others who would be more ideal? Just ask yourself how much time is enough.