Stuck in a bad situation. Any advice?

She fell in July and broke her femur. Also has macular degeneration so she is 75% blind.  Honestly she has gotten more therapy from home health agency then she did in nursing home. And yes she is slowly making improvements.
My uncle has POA and asked me to help, but he lives 8 hours away.

First, Gma is her sons' responsibility. They should be providing care or finding a safe place for her.

Now you. I would think this added stress is taking a toll on your MS. Working alone would be stressful. Maybe you need to talk with Uncle. Explain that you cannot be expected to this indefinitely with your MS. Decisions need to be made. I know there are better meds than even 10 yrs ago when my cousin suffered from MS. It was very hard for her to do daily tasks. Her husband did the majority.

You need to take care of you.

There is a reason there are shifts of people in a nursing home to care for people who need a lot of care. Trying to work full time and care for a senior sounds rather unreasonable to me. Is grandmother able to make arrangements for her own care? If so, I'd ask that she do it. If not, has she appointed someone as her Durable Power of Attorney? If so, then they should step up and make arrangements. Grandmother's DPOA or adult children can explore bringing in outside help for her or placing in a facility, depending on what level of care she needs.

Kimber is right. And don’t be worried that Dad and Uncle are going to be angry if you quit. You need your own life and you are not obligated to care for Grandma. If they give you a hard time, tell them it’s not up to you to make them own up to their responsibilities with her. If they can’t care for her she needs go back to the nursing home.

Why on earth did she "come out of a nursing home"? It sounds like she needs the care they provide. Is she competent in that she made the decision to come out? Who has POA? Sorry for all the questions but it helps to give a good answer if we know more. Apparently she cannot do all her ADLs so she should not be living alone. I agree with giving notice. This is your dad's and uncle's problem, not yours.

Give your dad and uncle a 2 week notice - you are done. They need to figure it out. Call Area Agency on Aging and tell them there is a vulnerable adult that will need help.