Making Me Sick!

ME:  How was your vacation?- to a male relative.

TODD:  It was great.

ME:  Who did you go with?

TODD:  My friend that I'm living with- I went with his wife.  He doesn't know that, but we did.

ME:  That is so wrong!  He doesn't know?

TODD: (paraphrased and shortened) Well it is his fault.  We were going to all go together, but he didn't arrange his stuff. I did my stuff, she did her stuff. He didn't take care of his stuff.  She told him she still he wanted to go without it.  He told her he didn't want her to go with me. I wanted to still go, so we told him that I was going camping while she went to Mexico.

ME:  That is so wrong! It isn't ok to lie to him. She shouldn't have gone with you.

TODD: He shouldn't tell her not to go if she wants to go. He could have come along. We had separate rooms... and she wants to lie to him.

ME:  But, it isn't ok for her to lie to her husband about it! He should be told.

TODD:  Well, I wasn't going to stay home, and she doesn't want him to know.  

Really?  Is it really ok to go on vacation for a week to Mexico with your friend's wife?  He let you move in after your wife divorced you and you help her lie/deceive him?  YOU GO TO MEXICO WITH HER???

This is not the first time I've seen this type of thing from these two people.  It makes me sick.  It makes me question humanity and morality and basic human decency.  

Am I the only one who thinks this is wrong?  Am I crazy???

I really want to tell the guy, but I only know his friend. I've met the wife and him once, but I never talked with them.  I wish someone had told me when Andy was deceiving me, and I wish someone had stood up to Andy to tell him it was wrong.  Instead, people just said it wasn't their business and let it go on. 

Where is that line between doing what is right and minding your own business?