Well, that is not STD worthy. You aren't going to get an STD from rubbing her breasts or her rubbing her breasts in your face. Why do you think this makes you so anxious? Guilt, I swear, can make us go over the top with anxiety. I see it here all the time. You have to let this go. If you can't, would you consider talking to someone about anxiety?
Well, speaking as a guy, it would make me feel pretty lousy because it's such a demeaning thing to ask a stranger to do and is such a tease without a payoff. But you know, different strokes for different folks, but I always liked it better when I believed (I wasn't always right about that) that the woman actually liked me. Maybe you're like that, too.