CHEATING - Where Do You Stand?

i was recently talking to a friend of mine about cheating and the concept of right and wrong, and who is right and who is wrong, and that i am always right ...

and, this is my question - if you have sex with someone (a cheater), who you KNOW is married or otherwise in a committed relationship (with the "innocent" party), are you "wrong" for that?

are you hurting the "innocent" party?

should the "innocent" party be angry with you?

does it matter if you don't know that the cheater is in a committed relationship?