Are you saying you knowingly have sex with people who are cheating on their partners? Because that’s unfair to the partner who is being cheated on. The person cheating on their partner is most at fault because they’re the one who committed to a relationship, but you’re enabling their behavior.
I once hooked up with a guy who told me he was single, only to find out he had a husband and kid, and had also lied to me about his name and occupation. I confronted him about it and he said his husband wasn’t fulfilling his sexual needs. My response was that was his problem to work out with his husband. I never talked to him again.