The minute I find out he cheated on me, he's out of my life but if he ends up getting a disease and never told me about it then I will hunt him down forever.
If he had it beforehand and didn't tell me because he was ashamed or whatever I'd be pissed of course but I'd show some compassion.
If he cheated on me and then got it and didn't tell me I'd probably kill him, yeah.
If he revealed his status within the first couple of dates, and before having sex, I'd be fine with it. He takes his medication, I take prep, we use protection and it's smooth sailing.
If he did cheated on me, contracted HIV AND had unprotected sex with me, I might kill him. And then I'd sue ha!