New mom bans MIL from being alone with the baby after what she did, 'I COMPLETELY lost it.' AITA?

"AITA for refusing to let my mother-in-law be alone with my baby after what she did?"

My husband Kyle (34M) and I (31F) just had our first baby three months ago. Since our son was born, my mother-in-law, lets call her Tremaine been overbearing, constantly giving unsolicited advice and making passive-aggressive comments about how I parent.

One of the biggest points of contention has been feeding. I'm exclusively breastfeeding, but Tremaine insists that formula is "better" because "breastfed babies are too clingy." I’ve told her multiple times that this is our choice, and Kyle has backed me up.

Last weekend, my lovely Tremaine came over to "help" while Kyle was out running errands. I went to take a quick shower, leaving her with the baby in his crib. When I came back, I saw her holding a bottle and feeding my baby formula. I was in shock. She saw me and immediately said, "See? He’s drinking so well! This is why I told you formula is best!"

I completely lost it. I took my baby from her arms and told her to leave immediately. She started screaming, saying she was just trying to help and that I was being ungrateful. When Kyle came home, he was furious at his mom but said I might have overreacted by kicking her out so abruptly.

Since then, Tremaine has been playing the victim to the whole family, saying I "humiliated" her and that I’m keeping her from her grandson. Some family members are saying I should apologize and let her see the baby again, but I don’t trust her anymore. So am I the ahole?

Here's what top commenters had to say about this one:

CptKUSSCryAllTheTime said:

NTA. Do not leave the baby alone with her. Let her know that she crossed a line and therefore her privileges of being alone with the baby are revoked. Until she can respect your parenting choices, she doesn’t get to be alone with him.

runiechica said:

Your husband needs to tell her and the family she was out of line. If he doesn’t do this and tries to keep the peace he’s not truly supporting you. NTA.

Fearless_logic said:

You are the mother and you decide what your child gets or doesn't get. End of story. She has NO RIGHT coming in to your home and disrespecting you like that. Not to mention the potential damage she could've caused. What if your child decided to refuse the breast after that? Or what if the can of crap she used had a recall which seems to happen a lot. I'm angry for you. NTA.

CarryOk3080 said:

Nta. What if your baby was allergic to that formula. She made an executive decision about a child that isn't hers. Therefore that child will never be alone with her again. Personally I would never even let her hold the baby again. She can see it from the couch sorry not sorry.

Infinite_Creme5578 said:

NTA, your baby, your choice. She disrespected your clear boundary.

carlared0nx190 said:

NTA. Your mother-in-law knew you were exclusively breastfeeding, yet she deliberately fed your baby formula behind your back. This wasn’t a mistake—it was a conscious choice to undermine your parenting decisions.

She put her ego above your wishes as the mother. You had every right to react the way you did. Until she acknowledges what she did and genuinely apologizes, she doesn’t deserve unsupervised time with your child.