Can my ex-fiance be held legally responsible for giving me an STD due to cheating?

I posted about a week ago that my fiance broke things off. I am lost.
It turns out he cheated, too. He's been with another woman (and me) since at least November. I am going to be tested for everything next week. I am disgusted.
I do not mean to sound dumb, but since we were in a committed relationship (engaged and a planned wedding), can he be held responsible for giving me an STD through her? Prior to her, we both had completely clean bloodwork and it is on record.
I apologize if this sounds naive. I really just want to throw up. What if I have HIV?