What do you think about my having sex with someone I know my boyfriend doesn't like?
What do you feel when you think that thought?
I feel so excited and naughty.
That is pretty petty of you to do that. You should break up with your boyfriend if you think so low of him.
He's known for a long time and I don't think it's a big deal
It sounds like neither of you are happy in this relationship, but that neither want to leave it. You should really consider just breaking up with him if your idea of fun is to cheat with people he hates.