Am I over reacting

So me and my boyfriend have been together for 2 and a half years and we work together. In March we broke up for 5 days and in them 5 days he texted this other girl who we work with saying let’s meet up and insinuated about doing things together. When we got back together I asked him to block her and not talk to her at work.

She’s recently been promoted so he’s had to unblock her number because he’s one of her bosses now. I’ve asked him to not talk to her at work. I know it’s impossible to avoid but I’ve said if it genuinely about work stuff then ok fair enough but he constantly walks about with her talking and laughing. I’ve asked him to stop and he just turns it round on me all the time and makes me feel bad about it all! Also she’s nasty to me at work and he doesn’t seem like he’s too bothered by it