A female coworker

Would it upset you if your husband, who cheated two years ago with a female friend, started trying to build a “friendship” with a single coworker from work thru texting all day, sending gifs and jokes, and talking about things before even talking to you about them? I’m at a loss. Advice welcome! He sees nothing wrong with it. To me, I don’t see why he needs to put focus on her when he should be putting that energy into us, especially since I’m still getting past the cheating... advice? I feel like a crazy person and don’t wAnt to ruin us. Please don’t advise to “leave him.”

Edit: he does show we what they text about, but I find it to be flirtatious on both sides. He finds it innocent, thus being so open about it.

EDIT:: i appreciate the thoughts and advice! I will speak up and talk with him tonight. It’s funny, I used to say I’d never stay with someone who cheated. It was actually while we were engaged and I didn’t find out about it until after we were married. He ended up telling me after some pushing from me (I had my suspicions but he always said to stop being jealous, it wasn’t like that.) we are amazing outside of issues with jealousy now and disagreeing on what’s appropriate vs what isn’t. Once married, I decided I didn’t want to divorce and we’d try to move forward. It’s tough- I am resentful and am trying to let it go but things like this make it so damn hard.