Help, I am in a "no-win" situation with my elder mother, brother, and husband! What do I do?

I so need to hear from others out there on adivce. I am very close to my 93-yr. old mother and 67 yr. old brother. My mother has mobility challenges due to osteoporosis and arthritis. She has a pacemaker, also. My brother was born with cerebral palsy and has been in a wheelchair all his life. He has no fine motor skills at all, of course, but he is amazingly resilient and types faster with a stick attached to a hat than many people do with their fingers. He was a football coach (believe it or not) for 35 yrs. at a college 3 blocks from our home. I've been married for almost 20 years and live 3 hrs. away from their home. Finally,
my mother's health issues needed more attention than I could give her from that far away and I persuaded them to move in with my husband and me. We've been trying for 6 months, but there are so many issues. My mother is so cold natured from the osteoporosis and my husband is very hot-natured. My mother wants the heat up higher so she will be comfortable, but my husband and I are so hot that it is about to make us ill. She has always been the sweetest woman, but age is making her very critical of almost everything. It seems there is always something wrong. They are afraid to stay by themselves in my home because it might be difficult to get out in case of emergency, etc.-even though I have portable ramps at both front and back doors. My husband and I feel as though we cannot go anywhere. Our home is not large enough for the 4 of us, but we don't want to move because it is our dream home on a golf course. They don't want to go to a separate home of their own or assisted living. I could send them back to the family home 3 hrs. away, but the doctors are nowhere near as good as the large metropolitan area in which I live. I couldn't be there to oversee her medical care, either. I would also have to hire someone to come in and drive my mother to drs. appointments, groceries, etc. She doesn't want to pay for that help as she is a child of the Depression and very frugal with her money. My brother gets help for 4 hrs. a day through Medicare. In addition to taking care of them and my husband I am a full time public school teacher. I am so stressed out and exhaused that I sit in my closet and cry so that the others won't hear me. I don't feel I have any options in their care. My mother and brother are "joined at the hip". She devoted her entire life to caring for him. After she passes on, she expects me to keep my brother living with my husband and me, but we will have absoloutely no life except for caring for him. We want to travel when we retire and would love to take him with us, but he has absoloutely no desire to do that. He would like to stay in the family home, but of course he has to have someone with him at all times to see to his personal needs. Everything revolves around him and his care. (By the way, his health is excellent and he take NO medications). It is so unfair to my husband and I can't do this to him. We are soulmates and he is the love of my life, but now there is a great deal of strain between us. I'm in the middle between them and him. I don't know what to do. Any way I go I have incredible guilt. Please let me hear from someone who has dealt with something like this----