Help me make sense of this ...

So, my boyfriend of 4 months cheated on me. I wanna say sometime in November... I didn’t found out until Dec 23 to be exact and then on Christmas Day I decided to retaliate and I slept with a previous partner... we worked things out, got back together started having sex again... then BOOM about 3 weeks ago I’m positive for chlamydia.. and I notified the guy I slept with and asked him to go get screened and shit and his test came back negative.. I’m not lying when I say I haven’t been with no one but the two guys I’ve mentioned.

My boyfriend claims that the girl he had sex with got tested the day after they had sex and everything seemed to b fine ... but you know in women it takes at least a month or more for symptoms to progress ... but I guess just recently she went and got tested and her test was positive... but I’m just tryin to make sense of it any help?

Let me know if I should provide any information... I honestly am confused like this is really absurd and idk what to do.

I’m just trying to figure out who’s end it could’ve came from it can’t be mine .. because the guy came back negative... but I feel like if the girl lied saying she was clean then we all would be infected ... there was a month in between finding out all of this so it’s hard to tell but let me know your opinion ladies!