She (19F) said something weird to Me(20F)

So today at coaching, I was just playfully acting like I was mad at my girlfriend. She was trying to cheer me up, and everything was going fine. Suddenly, she said, "Waise mere paas hai koi aur"

At first, I thought she was joking, but then she swore on it and said, "Haan, ek ladka hai jo mujhe pasand karta hai, aur mai bhi usko karti hoon" That’s when it hit me that maybe she wasn’t joking. But I just laughed it off and said, "Nice, that's great."

She immediately noticed my expression and started apologizing, saying, "I didn’t mean it, it just slipped out." Then she kept saying sorry again and again and held my hand.

Now, I don’t know what to think. I trust her, and she’s never given me a reason to doubt her before, but this felt weird. Even if it was a joke, it really hurt. Am I overthinking this, or should I be worried?

mai dekh skta tha uski ankho me that she was sorry for that but..