Am I growing up or being a self righteous asshole?

I had to tell someone today that I have been friends with for less than a year that I couldn't be his friend anymore. That is the first time I have ever actually done that to another person.

What happened?

I'll tell you. One of my married friends cheated on her husband with him.

I know, there will be debate on this. "It was their business and not mine", or "Why are you friends with either one of them?", etc.

Well, I've known her almost my whole life. Right now, we are on shaky ground, but we are friends. Sorta. I'm still sorting this out.

He. Well, I tried with him. I couldn't do it.

After four months of being in the middle between her, him, and her soon to be ex-husband, I was exhausted. I have encouraged him towards healthy AVAILABLE women. He wants none of that. He wants to take the easy route with my married friend.

I've lost all respect for either of them, really. I want to try with her because we have history.

Him, well, he's a snake with changeable morals. Our friendship would never be the same.

People are often surprised with how open I am that I despise adultery.

I am open when it comes to honesty. Cheating is about nothin' but selfishness, deceit, and manipulation. I hate that shit. You entered into an agreement to be faithful to someone. You be faithful or leave. I am not and have never been married, yet I have never cheated on any of my partners.

I myself am often surprised at how many married people don't seem to adhere to that same belief system when it comes to adultery.

I hope that I don't sound like a self righteous asshole, but I couldn't live with myself if I went along with something I thought was wrong.