Sister and her kids moving in with me and my parents?

I'm not sure what to do. My sister is contemplating on separation/divorce from her husband, she has 3 young boys and since she has no money and no where to go she would stay here with us. Despite everything her husband has done to her, she doesn't have the heart to stay in her house and make her husband pay, she'd rather both of them sell the house and live elsewhere. She will stay on the main floor with us, but I will let one of the kids stay in my room, even though I won't have any privacy at all and this will really bother me. She's going to save enough money and then pay us to renovate the basement so she can have the kids down there, but I think the kids will still sleep upstairs if the basement is still damp and this means I still won't have privacy. Has anyone else had this happen before? Are there any other options? I ask because the kids are so horribly behaved, my sister doesn't want to place this burden on my parents because the kids are absolutely intolerable and I'll go nuts. I'm not sure what we should do, any advice is appreciated, thanks <3 <3