Is it wrong that I'm thinking of letting it slip that someone's boyfriend was kind of flirting with me?
Why would you expose this person's boyfriend?
He doesn't want anyone to know about it and he is a liar.
I understand that you have a low vision of this person's bf, but telling everyone that he was flirting with you isn't right. Keep this information to yourself and stay out of it.
It's the best thing to do. He deserves it.
It seems that you would like to hurt the guy that was flirting with you. However, you should consider the impact that telling this secret will have on his partner as well. Additionally, if they don't believe you, it will be quite embarrasing for you.