Dear human being, if it was the same area,I would invite you to stay with me. However we live on different continents. I send you understanding and support.
I have similar,yet more complexed situation myself. I don't dare giving you advice, but I can offer sympathy and validation of your (really your sis's problem).
Finally, to ad, you're not defined by someone else's character flaws. Abuser is. Hope that relieves a bit of the heavy burden. Best of luck and be safe.