(Throw away acct bc my mil follows my real one)

My husband and I (both 25) were visiting my MIL’s house for dinner this evening. After dinner, my husband offered to drive his youngest sister to a friend’s house so that MIL could stay home after cooking. While he was out, MIL, SIL and I sat around in the living room chatting.

SIL is preparing to move out on her own soon, and was asking about any easy to cook dinner recipes I had. One of the things I brought up was spaghetti. When I said that, MIL chuffed and asked if I only make that when DH is working late. I was confused and told her no. She said “well, he doesn’t like spaghetti. That’s why I asked.” Again, I was confused. I told her that he likes it now, enough to request that I make it decently often. To that, she said “is it maybe your favorite thing to make and he knows it? Is that why he asks?”

At this point I started to get a little annoyed, because I could feel it going in the direction that she isn’t a stranger to, which is the “I’ll always know more about my son than you” sort of thing. So, where I would usually just shrug and say idk to keep the peace, I decided I would push back this time. I told her that every time I make spaghetti, he polishes off over half of it that night, and left overs don’t last either. Then, MIL turned to SIL and said “you remember how much he hates spaghetti. He would practically gag over it.” To which SIL shrugged and said “maybe he changed his mind.” And MIL went on to say “no, I know him. He’s stubborn about tastes.”

So I asked MIL if she thought I was lying about him liking spaghetti, and she rolled her eyes and asked me if this was the hill I wanted to die on. To which, I said that she was welcome to ask him once he got back. She shook her head and told me there was no need for her to ask. That she knew her son and she would know the answer.

After that, conversation faded and we all sort of just got on our phones. Until, my husband walked back into the house, and the first thing I said was “hey babe, do you like spaghetti?” And of course, he said yes in a confused tone. I gestured my hand to him and looked at my MIL and said “see?” And she got up and said “I gotta do something” and went back to her room and did not come back out until we left.

On our way home, I explained the spaghetti thing to my husband, which he honestly did not care about. He’d just asked why I asked. But about an hour ago, MIL sent my husband a big text about how I was rude and telling her that he only likes my spaghetti because I’m a better cook than her (which I did not say.)

So, AITA for arguing it? Does it make me childish, even though I was a little fed up with the whole song and dance?