AITA for kicking my mother and her baby from my engagement dinner because they ruined it?

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The original was posted on /r/AmItheAsshole by /u/Glass_Honeydew3415 on 2023-06-27 08:09:37+00:00.

Backstory: I (28f) have been together with my now fiancée "Luke" for 10 years. We have 2 children aged 3 and 18 month. I am currently 3 months pregnant with our 3rd child.

My mum "Sandra"(48f) has recently had a baby with my bio dad, the baby is 2 months old. I don't have any sort of relationship with my bio dad as he left my mum when I was born leaving her alone with me and my older sister. We have a step dad Mark who i call my father, he has divorced my mum after finding out she is having an affair with my bio dad.

To the events: I have always dreamed of a romantic proposal which is something Luke was aware of. He has prepared and booked in a room in a high end restaurant, had it decorated for the event and also had his friend to take and edit a video of the whole thing (his friend is a professional and does fantastic videos). Luke also invited people close to us, so my friends, my sister and her wife, Mark and my mum. As this is a high end restaurant it doesn't accept kids under the age of 12 and has a warning about it on the website. Luke has also asked people invited to keep their children at home (the booking was made a good few months in advance). We have hired a trusted babysitter for ours. It is also important to note that he knew we won't be able to get married soon until our kids are older as I wanted them in our wedding and somewhat to remember it.

At the event we found out my mum took her baby with her instead of leaving him with my bio dad. When I have asked her about it, she said the baby is quiet and it is not her first child so she knows how to look after them.

Well, when the music started playing (it started rather quiet) and my fiance was ready to give a speech, the baby started crying. Luke has tried to carry on but nobody could hear him due to the screeching sounds the baby started to make, and I was feeling overwhelmed with it as my romantic proposal was getting ruined by my own mother being selfish. So I have asked her to leave.

My mum has tried to argue to stay and was creating a scene, but I ended up asking security to escort her out. The rest of the day went without issues but after the event was finished I have received dozens of messages from my mum and bio dad calling me an asshole for what I did.

Edit: paragraphs.

Also wanted to add, the child in question is not my mother's biological child. The child biological mother is one of my bio dad's girlfriends who wanted nothing to do with him, so my bio dad and my mum adopted the kid. My mother is also insisting her grandchildren to call the kid uncle, which is something me and my sister are against of (one of my sister's kids is 8 and therefore are older then the child).