My mom is in the hospital she says she "can't walk" but refuses rehab care, is there a way to make her go?

I have been caring for my mother essentially my entire life. From bathing her when I was a child because she would get drunk and urinate on herself (or worse). I left home at age 14 because my "parents" were abusive alcoholics. Now that she is older, my father is dead, she lives with me. Because she pissed away all the money she had, now she only has my dad's social security (she didn't work enough in her life to have SS credits) anyway, back to the question. She has a clotting issue from smoking for 50 years, she is constantly having to go to the hospital for surgeries. She has lung cancer metastatic to the brain. She has been alive with this condition for five years, she is 68. Currently, she is back in the hospital, the doctor told her she needs to go to a rehab hospital till she is able to function without Assistance. Her response to the doctor? Hell no! That's right, she expects ME to care for her, bathe her, feed her, take her to appointments, and be at her disposal. One problem, I have a child with autism, I have a husband, a full-time job, a life! Although she lives here, I didn't take her to raise, especially a 68 year old baby who will do nothing for herself. Guys, what I am asking is do I have ANY reprieve? She will not sign a Power of attorney, I have a sister who is ZERO help. I have no other help, she told the wound care people not to come back after last surgery because her daughter would do it! What can I do? I feel I am in a no win situation and I am so sick of being her whipping post, the door mat. She is selfish and unrealistic. I just want to have some sweet relief. I called the hospital and told them to please have a caseworker call me! No response. She has Medicare they will keep her in rehab 100 days! but it's like she is intent on coming here so she doesn't have to do anything to try and get better. I know this sounds cold, but I am really ready for her to be out of my life for good! I can't take it anymore!! I am so exhausted and my child and family Must come first, I promised I would be the parent I never had! I wasn't a priority for her or my dad as a child, why should I make her a priority? I'm so frustrated! My sister is older, my mom gives all the doctors her info for contact, not me, I only get second hand information. She is literally bleeding me dry, financially, emotionally and physically. What, if anything can I do? I'm so tired of "caregiving". Lately, I have begun to lack compassion, not that I don't care, but if she senses the slightest bit of concern, she preys upon it, and uses it for leverage, it feels like emotional abuse. Please help!