How would you react to finding out you were making out with a transsexual?

[Yonadav]

I would advise telling a man before you sleep with him if you are pre-op, preferably before engaging in other forms of sexual activity. You don't need to justify or apologise for your existence despite what the right wing claim. I don't know about America where the conservatives are fighting back, but men can be surprisingly open minded, more than you might first expect if all you know of them is violence.

If you are post-op, he doesn't realise and you're not starting a relationship then it's not a problem as he does not need to know. After all, would you give him the rest of your medical history before having sex?

I don't think that you can invoke confidentiality of medical history between people who are considering getting intimate. There are things about a person's medical history that are absolutely a prospective intimate partner's business.

At the end of the day, there are many, many men who would not knowingly consent to intimate relations with a woman who used to be a man. Since they would not knowingly consent, then it very, very clearly falls within the category of date rape.