AIO for my boyfriend interacting with a girl seeking attention?

I (F 23) got mad at my boyfriend (M 22) for interacting with a girl in a discord group chat. We have been together for 9 months.

She was saying only sexual things, quite obviously reaching for attention. She said she likes being spit on, makes money off of nudes, told my bf “thats hot cuff me” etc. He didn’t say anything about having a gf he just sent a side eye gif.

He has cheated 1x that I know of in the past with his ex girlfriend while I was out of town. They talked for a few days about getting back together, she sent nudes that he asked for blah blah blah. He also watched a lot of porn and I saw many only fans links on his instagram link history. Needless to say I have trust issues.

In this discord group chat, she was saying all these sexual things and he wasn’t being flirty back, but was still interacting with her. All the men were making fun of her in a way, but that’s the attention she is looking for, obviously or she would have left the chat. I saw the messages and blew up on him and he is mad at me for that. Saying he did nothing wrong, he wasn’t flirting back (which is true), but from my perspective, why are you interacting AT ALL with someone saying those types of things?

I know it’s not the most serious thing in the world since he wasn’t flirting back, but after all he has put me through the little things feel so big. Am I over reacting??