Why would my partner not tell me she has an STD?

I feel heartbroken. I met a girl last year at a friend’s birthday party. She was breathtaking and I couldn’t help falling for her. Lon and short of it, she infected me with herpes and staph.

I am sure she knew all along before we met, and I was really serious with her and hoping that our relationship would get somewhere. why won’t she tell me that she had infections or at least warn me to use protection? She was the one who starting asking for raw intimacy after the first few months. How can someone be so wicked?