Am I overreacting ?

Please I need your guys help, my bf and I recently broke up because he thinks that i cheated on him but I didn't, I few months back in September my bf left for bootcamp and I when to go see him off and I had intercouse with him and a week later since I recently turn 21 I decided to go do my "women" check up where they test for breast cancer and check my cervix after a week of my bf being gone and since I got my check the doctor told me to come back and said something was wrong with the cells in my cervix and that I also had chlamydia, this was a shock to me because the only person I have been with was my bf so I assumed he cheated and when he graduated bootcamp I asked him if he cheated on my because I tested positive for chlamydia and I haven't been with anyone else besides him and he said no I couldn't possible have gotten it from him be used they test for it before he leaves for bootcamp and during bootcamp and he tested negative both times and then I said ok I trust him after that he started accusing me of cheating Abe use how could I haven't gotten it if he doesn't have it and if I had it the whole time how come he didn't get it and tested positive before he left, I went back to the doctor and got tested and the results were negative but this was a month after I had already took the medication to clear it, I asked the doctor how could that be possible that I have it and he didn't and she said it could've been a false positive or he could've test false negative but that highly unlikely since he tested three times, we recently broke up because he couldn't believe I didn't cheat but I really didn't cheat on him and I have no way to prove it, I offered to take a polygraph test but he doesn't want to. If you guys can help me that would be great!