AITA for not allowing my MIL to stay with us during her pregnancy?

I (F19) have been dating my boyfriend (M19) for 3 years. He has two sisters, one of which is currently 9 months pregnant with her first baby. My mom had me and my sister very young, so her mom (my MIL) stepped in to help raise us when my father kicked my mother out. My MIL has always been very controlling and tried to "improve" my mother, trying to get her to dress and act like her, and pretty much calling my father a piece of shit for not being there. My mother did not like this, but she needed help, so she put up with it. When I was in high school, my mother realized that she wanted to travel, so she moved to another state and left my MIL to take care of me and my sister. MIL hated this and constantly complained that she was not a real grandmother and that she could not "raise" us because my mother was there.<br><br>My boyfriend has the one sister who is currently pregnant and the other sister is not married and does not have kids. His father died of a heart attack when my boyfriend was 16. MIL preaches how he should have taken better care of himself, since his heart was "broken" from the death of his son. My boyfriend's older sister has a history of mental illness, so my boyfriend and his sister's husband decided that she should move out of the house and he would take the baby when she gave birth. My boyfriend's sister has chosen me as her childhood best friend to go to her throughout this pregnancy. I have done everything for this pregnancy that any best friend would do, like dress her baby, pick out nursery themes, help her find a doctor, etc. <br><br>When I was pregnant with my son, I had a very difficult pregnancy. I threw up constantly, had constant migraines, and I could not stand for longer than 10 minutes without passing out. My MIL called me every day asking me when I was going to come home so she could take care of me and help me with my symptoms. When I delivered, she called everyday asking when I was going to come so she could help me. When I was too sick to drive, my boyfriend ended up having to take a day off work to drive me home and take care of me. My MIL came over, but I could tell it was out of obligation. She did not want to help me, she just wanted to say she was taking care of me. I was disappointed, but my boyfriend said I should not bother her for anything else because she would just complain. <br><br>Fast forward to my boyfriend's sister being 9 months pregnant. My boyfriend and I had discussed that we would not allow MIL to stay with us if she did not help his sister during her difficult pregnancy. When his sister began showing, we told MIL. His sister has also expressed that she does not want MIL in her business. MIL complained but said she would follow the rules. <br><br>When MIL's daughter delivered her baby, she showed up at our house with a suitcase. She said she was going to stay with us until her daughter recovered. I told her she was not allowed to stay, and she had to help her daughter. MIL flipped and said since I had it easy when I was pregnant, I could do nothing to help someone else. I told her that her actions when I was pregnant proved that, and she had her chance and she blew it. She got mad and left. Now some of my boyfriend's friends and family are calling him a jerk and saying that it was wrong to not let his mother see her grandbaby. I have been told that I am ruining the relationship between MIL and her daughter, which is not true because they were distant even before the baby was born. AITA?