Not sure if I should feel this way

Earlier this year I found out that my boyfriend of 7 years whom I live with also (have our own place together) was flirting and sending messages and getting romantic with a girl from his work. Started noticing his behaviour for months until I decided to look through his phone and he of course forgot to delete the messages because the messages were only sent that same day but they’ve been talking for 2 weeks straight behind my back. He bought he flowers for her birthday (she took pics and sent it to him) and they were just sending each other hearts, baring in mind he hasn’t bought me flowers let alone a single rose for nearly a year. I was heart broken, I confronted him and broke up with him and threw him out the house. He was regretful for what he did and was begging for me back and said he messed up, despite for what he did I am still finding it hard to let go of what happened because of how sick I felt and traumatised. I am starting to feel that I have PTSD for what happened because my ex boyfriend before him cheated on me too.

I keep crying and getting emotional time to time but I love him and know that he loves me, we’ve just come back from a sun holiday from Turkey and he was loving however I feel that coming back home he hasn’t been that affectionate as he use to be again and he’s on the verge of becoming redundant from his job, he started looking for another job in becoming a personal trainer at the gym (something he is passionate about) so I commented going “oh so you think it’s ok to personal train other girls, what if you start flirting or she starts flirting and you take her number behind my back like you did with the other?” I’ll be honest I feel that I shouldn’t be saying that and acting that way but because of what he did to me I feel that it’s permanently damaged me and scared he will hurt me again. What pissed me off is that he didn’t even bother to reassure me? His response was “you’re acting stupid, I am passionate about this and I don’t care what you have to say”

Of course I hit back and said fine I’ll get myself a male PT to help me, he didn’t even say anything back to that. Is this a little thing that I shouldn’t worry about? I’m starting to feel down and contemplating the relationship now thinking that I know for sure he will hurt me again.

Advice welcome?