STD’s and my partner - afraid he’ll leave

So to give a little backstory: me and my boyfriend broke up for a couple months. In that time I was completely done and slept with someone else (I will always regret it). I got tested frequently but unfortunately due to trusting a friend (we were friends before we had sex) that I shouldn’t have I contracted Chlamydia. I was extremely hurt since we were sort of dating and that meant he had cheated recently. Since I tested frequently I caught it and took the medication for it. However, before I found out I had it, me and my ex showered together but didn’t have sex. He didn’t need to know what happened while we were on a break but out of respect to him I told him about the infection and he even said that’s something I didn’t have to tell him. I am testing again next week to make sure that I am still clean. But for some reason I got worried that from that shower somehow I gave it to him and he gave it back to me. I know In my head that’s not possible but I’ve been so worried about it I’ve gotten like itches down there because I believe I’m manifesting it. I didn’t keep anything from him and made sure to not have sex or anything after I found out. If on the crazy coincidence that it got back to us, would you leave? I did not have sex with him before the medication was complete and I even got tested right after which my doctor said I didn’t have to. I would Never be so careless or disrespectful of his health because I was devastated when it happened to me.