Help!!!! Roommate situation

So when my brother and his girlfriend got pregnant last year I told them they could stay with us and rent would be $200 they have a whole furnished basement with their own bathroom and shower they also have access to the laundry room which is in the basement. So she was 4 or 5 months pregnant when they moved in well now their baby is 7 months old born in March and they told me they were moving out in April when they had moved in well a few months ago he had also told my mother and father that they were planning on living with us for 2 years? I had no knowledge of this. I wanted to be a supportive sister because my brother was finishing up his degree in college and was supposed to graduate May 2017 well he ended up dropping out and then retried this spring semester only to drop out again! He decided to buy himself a brand new 2018 truck instead of looking for a place to living with his little family? The worst part of this is I’m having a baby on the way and I want my house all to myself. I’m tired of cleaning up after 3 other people because they leave their babies crap everywhere and the basement is alway disgusting with old bottles that haven’t been washed out, clothes everywhere, diapers on the floor, pizza boxes laying around with old crusty pizza in them, toilet is never flushed so you can smell stuff as soon as you walk down the stairs. I’m just tired of it and I’ve talked to them before about it but I’m tired, I’m tired of pulling my hair out and stressing when I should be calm and relaxed for my little growing baby. I want to give them a time and date set for moving out but I don’t know when would be reasonable? Honestly the rent money isn’t even worth it anyway I don’t like living with people who are sooo damn dirty. Any advice? Also i live in Minnesota and it’s October it doesn’t really snow until November ugh helpppppp!!!! 😩 this is a serious issue. Going to post this in parenting because I’m not sure where else to put it.