AITA for not sharing my siblings with my new born niece?

I (19F) am a first time mom. I have a newborn baby girl (5 weeks old). I have two siblings (17m and 13f) who are in high school currently. Since I became a mom, my siblings have been more attached to me and my baby. They help out with babysitting.<br><br>Three weeks ago, my brother turned 18 and invited his friends over. Most of the guests were his high school classmates who went to the party with their friends. Since my siblings live with me, they were there too. My baby was asleep when they arrived. My siblings were supposed to wake me up in case she woke up but when one of her classmates (also 18F) spotted the baby, she walked over to the room where my baby was. I woke up to my baby wailing. When I looked up, there was a young girl holding my baby who looked like she was about to cry.<br><br>All her classmates were youth friends (some of them were strangers). I didn't even see my brother.<br><br>I rushed over to my baby and tried to calm her down. I also asked this girl who she was and why she wasn't supposed to be there. She said she was friends with my brother and that he invited her. I told her to leave and to never hold my baby.<br><br>My brother said I was being an a$$hole and overreacting. I said she had no business holding my baby when she doesn't even know me and is not family and when she was only here for his party. He said she wasn't a bad person but I told him to keep his friend away from my baby.<br><br>He then said my attitude was not good for my reputation. I said he had no business telling me about my reputation when he didn't ask for my permission to invite his friends. He got mad and said I was rude.<br><br>He then said I was born with a silver spoon and raised in a wealthy home as a princess. He said I should live my own life and not use my past as a reason to be mean to people. I said he was not supposed to be judgmental and make assumptions about me just because I had money but he said he saw the result of me being spoiled and rude. <br><br>Now he's making nasty accusations against me on social media. He's saying I'm a mean person and I alienated him from his sister (me). I don't know what to do.<br><br>&#x200B;<br><br>Edit: To clarify, this is my brother's friend and NOT my baby's father. My baby's father lives with me and is my husband. I also already apologized to my brother and sister for snapping at them. I do not need any more comments.