what would you do ?

i’ve been staying with my husband and his mom and little sister for a little while now. i really love his mom, she’s an amazing women and very hard working but also hard to live with. we’ve been saving to move out the past 2 years. his mom and sister are just.. well to put it nicely they don’t like to clean after themselves, we can’t have anything nice in the house cus it gets ruined, and they have a small roach problem. just to keep it short. anyways, my parents own a 2nd house which they do not use, my sister lived in it for awhile but moved out. my husbands mom had asked about renting it from them a couple years ago but it just didn’t work out. my parents offered to let me and my husband rent the house.. but just me and my husband. we want to start a family, i want to be able to have my nice things without them getting ruined, most of all i just want to be able to have a clean house. it got brought up in conversation about my sister moving out the house and mil immediately started asking about her renting it. i feel really bad because she’s a single mom and works really hard to afford all her bills and rent which i know she’ll struggle to pay by herself once we move out and i would love to help her but also i just want to live on my own with my husband and start my own family. am i being selfish ? i just honestly feel guilty for some reason and i know if we tell her my parents are letting us rent it she’ll want to/expect to move with us. like it’s to the point where i told my husband we shouldn’t even tell his mom that it’s my parents house that we’re renting (she’s never seen it in person so she wouldn’t know) i’m just so conflicted on what to do.