Do I tell or don't I?

[big fella]

This may get a little long winded, sorry but I need to give the background to the story.

About 10 years ago, the company I worked for was taken over by another. Most of the mechanics on the floor (me) stayed. The new owners brought some of their own mechanics and their spare parts workers from the dealership they sold to buy the one I worked at.

One of the spare parts guys that came with the new owners was about 19, quiet, reserved, a bit green and naive, but very good at his job. Not long afterwards, a female delivery driver was employed, who was about 22. She seemed nice enough, was a little bit flirty, and had lived a bit, if you catch my drift.

She and another female staff member used to enjoy embarressing the young man by talking a bit dirty in front of him, and acting a bit tarty. This carried on for 6 months or so, until she finally reeled him in and had her way with him.

They became attached, she moved on workwise, but they married and are still together. He left work for 12 months to start his own business. He worked 14 hour days, 7 days a week. The business failed, and he returned to spare parts.

I left work there in 2002. I kept in contact with a couple of techs, but not the spare parts guy. I would occasionally call in, and when I did, we would catch up, but we were never what you would call mates. I hadn't seen him for 6 months or so. A new supermarket opened in my home town, and my wife was lucky enough to get a job there. On my first visit to the supermarket, after I had finished work, I was served by the woman who had worked at the dealership. It turned out they had moved to a neighbouring town. I introduced her to my wife and they became friendly.

The friendship has soured just recently, it has become apparent that the women, who is now 32, married with 2 kids, is playing up behind hubby's back with an 18 year old shelf stacker. As I said earlier, I was never really close to her husband, but he is a great bloke, who thinks the world of his wife, and works his guts out for her and their kids. I would love to let him know what she's up to, he deserves better. But my wife insists that it would make her job unbearable, and in the end it's none of my business.

The thing is, if the tables were turned, I would want to know, and I'd be p15sed off if I found out that people knew and didn't tell me.

Do I tell? Or do I keep my mouth shut?