Is telling someone's dirty secret for sex because they hurt you wrong?

A friend of mine has always been choosing people over me time and again even though I have been the one that has stood by their side, supported them with a place to live, food to eat, and financially to help them back on their feet. I told them how I feel about them and they said they understood, but that they were not physically attracted to me and that was the only thing that could not allow them to give me a chance. I feel used and taken advantage of and know they have done a porn, but don't want anyone to know about it. I know it is mean, but I want to make them hurt as much as they did for breaking my heart. They have sent me mixed signals, flirting off and on, leaving their door open so I see them changing or naked, and then pushing me away when I try to be close to them. I am so hurt and angry and the truth is it would not be as bad if I was not sexually attracted to them. So my question is, would me telling them I would tell their secret in retribution wrong? I am a woman scorned, used, and taken advantage of.