Search Results: slept with a guy with a girlfriend

So me and my Girlfriend have been dating for 3 months, I recently found out she had Chlamydia (I haven’t been checked yet but she was and she obviously passed it on to me). I asked her if she was clean early on in the relationship after the 4th date before we had sex and she said that she got tested with her last boyfriend and she only had one possible partner in between that time (and she made it sound as if the guy she slept with wore protection and didn’t sleep around). I told her today she should probably inform him that he has it and she said she doesn’t know who gave it to her cause there was supposedly multiple men. Now I was initially a little upset cause I trusted her word but now I obviously know she lied to me. Now I also find it weird she got an STI checkup midway through the relationship (2 weeks ago) when she’s had other doctor appointments before that in the relationship (as she had to refill Birth control a couple times and get checked up on for a cold). She also won’t talk about it with me about it (or anything to do with it), when ever I bring it up she gets mad at me and says I don’t deserve to be upset about it.

I do love her and I think I can get over the fact she passed an STI onto me (though I feel shame for myself because I obviously have an STI atm) but I’m mostly disappointed and upset with the fact she lied and I likely caught something because of it. What should I do?

(Also I’ve only ever slept with 1 other woman and got tested fight after and was clean, so I couldn’t had passed it)