if I were you I'd tell the wife. You don't need homewreckers like that in your life either

Know how this feels only the chick wasn't my friend, although I tried to be her friend at first, and my sons dad was the cheater. There both home wreckers and she knew we had a child and everything. He was taking my car to bring her on dates and was a dick nozzle and this was all at work because we all worked at the same place. I know how this feels and I can honestly say it's not worth your time to be her friend and the wife deserves to know what's going on.

Sounds like Cameron Van Buren from MPGiS

She's your friend. You don't have to agree with her decision, but it's not your place to judge her. Personally, (having been cheated on by almost every boyfriend I've had) I think that your friend's boyfriend is a jerk for betraying his wife. But, also, your friend probably feels lousy for her actions or has low self esteem and doesn't think she's worth more than being a secret... Who knows what's going on. I'd be more worried that my friend is in a bad place, rather than berating her actions while in that state.

Chances are she already knows how wrong it is, but is so desperate that she doesn't care. As much as it sucks, it's not your problem, OP.

OP here. It's been three years since the incident, and I finally took the time to read all the comments and figured I can now do a complete follow-up. My best friend and I were in our senior year of high school, and the married man she was seeing was a few years older than us. I didn't know him or his wife. Basically, the guy had a long-term girlfriend who he left because he moved across the country, where he met my best friend. She dated him and lost her virginity to him, so he was her "first love" and that whole deal. He went back to his old town to visit friends and family, slept with his ex, and then came back to my best friend who didn't know. He found out his ex was pregnant, dumped my best friend, and married his ex who moved across the country to be with him and raise their family. My best friend was heartbroken, but I guess he was telling her that he still loved her and was only married to his wife because she was pregnant, but he would eventually leave his wife for her. She- being vulnerable and young- believed it and kept seeing him. Looking out for my friend's best interests, I tried to tell her that what she was doing was wrong- not just for the wife and kid, but for herself, because he obviously was using her and had no intentions of leaving his pregnant wife. She didn't like what I was saying and essentially told me to **** off. I didn't tell the wife (even though I wanted to) because I didn't know her and didn't need my best friend to be mad at me. I was kind of afraid of her because she has a very aggressive personality and I've always been very passive. But anyway, she eventually found someone else and ended things with the cheating asshole. It took some time though. Nevertheless, her and I are still friends. We dropped the "best" though and I keep her at arm's length because new incidents have arisen throughout the past couple of years that made me realize she doesn't deserve my friendship. Karma also helped a girl out and I'm happily married while she still searches for someone who will love her despite the fact that she's crazy. And you best believe I've been keeping my husband far away from her. Thanks for reading! Sorry this was so long.

Sometimes you have to let people figure it out for themselves.

Well she was right, having morals tends to decrease your chances of getting laid. But it's still better to have morals