AITAH for letting my boyfriend get a taste of his own medicine?

My (29F) boyfriend (27M) has this habit of constantly calling me “dumb” or “stupid”. It started as a joke, and at first, I laughed along. But over time, it became his go-to way of addressing me, no matter the situation. I asked him, begged him to stop, especially in front of his friends, but he would just chuckle and say, “What? But you are dumb.” His friends even picked it up, and now they casually call me dumb too. It’s humiliating.

I started avoiding his social gatherings because I knew I’d just be the butt of their jokes. Whenever I told him how much it bothered me, he’d just say I was being too sensitive and that it was just a joke.

Last night, I hosted a party with my work colleagues. It was important to me because I work in a competitive field, and many of my coworkers are incredibly accomplished. I introduced my boyfriend to everyone, hoping he’d be on his best behavior.

But of course, he wasn’t.

Barely an hour in, he started the dumb comments again. My close work friends are used to me venting about this, but one of my senior colleagues—an incredibly sharp, no-nonsense woman, was clearly unimpressed.

She turned to him and said, “Hey, you’re a guest here, and you do realize who you’re talking to, right? Maybe cut the ‘dumb’ comments.”

He just laughed, like he always does. Then later in the evening, I accidentally dropped my drink while reaching for it, and right on cue, he loudly called me dumb again. That’s when my senior completely shut him down.

“You know, everyone in this room has either an advanced degree, multiple certifications, or years of experience in their field, including my name, who’s one of the smartest and most competent people I’ve worked with. The only person here without those credentials is you. So if we’re talking about intelligence, you’re the least qualified person to judge.”

Dead silence.

For the first time ever, my boyfriend had nothing to say. He went completely red and barely spoke for the rest of the night.

When we got home, he was livid. He said I should have defended him, that I “let” my colleague humiliate him, and that what she said was “unnecessary and cruel.” I just looked at him and said, “So now you know how it feels.”

He’s sulking and acting like I’m the bad guy. For what it’s worth, my senior later apologized to him before leaving, saying she didn’t mean to be harsh but was just looking out for me.

Now he’s acting like I betrayed him, but I can’t bring myself to feel bad. After years of him publicly embarrassing me, wasn’t it fair for him to finally experience what he put me through?

AITAH?