Thank you. Most people are blaming the mom, and while it was mostly her fault, this man contributed as well. You can't blame the kid for being pissed with the principal. You know good and well that you would be too.

I would consider the cheater more to blame than the person with them. THEY made the promise and THEY decided to break it. If the person knowingly gets with them, yeah they are a dick; but not as much as the person in the relationship. If he has a family too, that's between his FAMILY and him, just like this should be mostly between op's family and op. I doubt op would like the guys kid(if he has one) waltzing up and punching his mother.

You can't say for sure that he knew he was sleeping with a married woman, he very well may not have. Lots of cheaters make sure to never mention anything that might hint at them not being single, and some even purposely live multiple lives with multiple SO's, all of whom assume they are that person's one and only. I once discovered that the guy I had just started seeing was already with someone when she texted me, calling me a **** and a home wrecker and a dozen other nasty things. I felt bad for her, but I hadn't known she existed, and I hadn't purposely or knowingly helped him cheat. I wasn't the one to blame, he was, for cheating on her and lying to me. And I always wondered why she never once thought to blame him. So it always bugs me when everyone automatically blames the other person, especially without knowing the details. They could be innocent just easily as not, you have no idea until you have all sides of the story.

I would definitely be furious with the guy too. But the problem is that op never said anything about the mom and said the guy was "the reason" his parents got divorced, and that's just not true. The mom cheating is the reason his parents got divorced (or at least one of the main reasons), and when parents divorce it has to do with the parents, not outsiders. The guy is definitely a jerk, especially if he knew she was married and had kids, but he's just a jerk. The mom is the cheater. She's the one that made vows and broke those vows. People are bringing that fact up because op seems to blame this guy instead of his mom.

yup, got to hold everyone to the same standards if not don't pass judgment.. good point brother.

OP never said he wasn't mad at his mom. He could be just as mad, but didn't mention it because the FML was about whoever handed him the diploma. Also, this guy destroyed a family and caused unneeded distress to OP. I think OP at least has the right to be angry at his principal or whatever.