AITA for banning my husband's sister from our house after she tried to dump her sick baby on me to make it to a party?

I have been married to "Alan" (M34) for 3 years, we also have a baby girl (1). Alan comes from a big, tight family. His parents, us, his sister ("Lola F35), her husband ("Greg, M37) and their twin boys (3) all live in the same neighborhood. So we see each other often.<br><br>Alan's sister, and in a smaller extent his parents, expect me to be more involved in caring for the boys, and helping Lola with the house and chores. She's a stay-at-home mom. I am also a stay-at-home mom. I was working before the baby arrived, but I stopped after having her. The original plan was for me to go back to work a year after giving birth, but I changed my mind. <br><br>I love my baby girl, and I feel really happy being a stay-at-home mom, even though it's hard. The problem is that my in-laws, especially my sister-in-law, think that I have plenty of time and energy to help them out. And I do help. I take the boys to school, and I help her with chores, errands, and babysitting. I enjoy it when I can manage that is. Alan has also talked to them multiple times about giving me space to be a mom too. It hasn't made any difference.<br><br>Last Saturday, I was planning on having a movie marathon with Alan after putting the baby to sleep. I did all the housework, it was already late afternoon, we were cooking dinner, and we were thinking about what movie to watch, when the doorbell rang. I was expecting it to be my MIL with the boys as I had promised to take care of them for a few hours.<br><br>To my surprise, it was Lola. The boys were with their grandpa, she said. She had a sick baby with her though, her friend's girl (3 years), whom she was supposed to babysit for 2 hours, till the friend came back from picking up medicine for her other (also sick) child. She said she couldn't take the girl with her because she had plans with her husband and his friend, and the baby was sick, so she asked if I could take care of her till her friend came back (2 hours max she said). I said no, because I had plans with my husband that I didn't want to postpone. So she asked Alan. He said no too.<br><br>She got upset and started shouting at us, saying that she only asked for "one little favor" and that I always have plenty of energy when it comes to taking care of her kids, and helping her with housework, but when it comes to doing her a solid favor, I conveniently play dumb. She also said that I was being selfish for not helping her have a night out. I told her that she has no right to speak to me this way, especially since I do a lot for her family anyway. But she kept pushing, and I bent. I said yes, but only *if* she rescheduled with Greg and his friend. I said this because I was afraid that her friend would show up late, and that I would end up having to babysit the girl for more than two hours.<br><br>She refused, saying that she'd already rescheduled once, and that they were expecting her. I said no again. She left, saying that I've proven myself to be a "selfish baby with no heart". I was really upset. I told Alan that I wanted her to not visit us for a while, at least till she apologizes. Alan agreed, and said he'd talk to her.<br><br>On Sunday, he talked to her, and she did not apologize. Instead, she told Alan that the party was a blast, and that her friend's girl recovered. Alan told her that she is not welcome in our house for the time being, and that he expected an apology. On Monday, their mom came over. I was out with the baby, Alan was home. He told her the same thing he told Lola. She said that Lola was stressed, and that I should be more considerate of her, and that I should allow her to come over "in case one of the boys got sick". Alan said no.<br><br>The thing is, after Alan told his family that Lola wasn't welcome, I have been getting hints from them. Yesterday, my FIL hinted that my sister-in-law is my family and I should let things go. Today, Greg dropped off the boys (I wasn't home), and according to Alan, he said something on the lines "you know, my wife feels really bad that she can't visit you guys anymore". Alan is getting pissed. I know I did nothing wrong, but I am wondering if maybe I could have managed to babysit the little girl. Honestly, I can't afford to catch whatever the baby had because I don't want to risk getting my baby sick, but maybe I could've helped.<br><br>AITA?