STI HELP

I recently went to my gynecologist to get a check up and I just found out I have chlamydia. Now here comes the difficult part, I have been talking to this guy for maybe 4 months, now mind you before I became serious with this guy we were just fwb and we decided to take a month off before we decided we really wanted to try something serious. During our month apart I slept with someone else one time, and when we decided we were going to be fully dedicated to each other he had asked me if I slept with anyone else during our month off and I told him no. And I should of told him the truth but I didn’t feel like it needed to be mentioned. Now I told him about the STI and wants to cut all ties with me. So should I let him go or try to talk it out with him.