Playing devil's advocate here
It's very easy to jump to conclusions when you only see one side of the conversation. He may be chatting her up and your wife has given him the brush off. On the other hand she may have given him signals previously thinking it was harmless flirting and he's taken it too far now.
She may be craving a little male attention if you have been together for 20 years. Women do like to think they are still attractive.
If you have been together that long I would sit down with her, explain how you came to read the text and the fact you can't get it out of your head.
You should know her after 20 years so watch her reaction
Insecurity can play very hurtful tricks on you to the stage where you convince yourself it's the worst case
Talk to her mate
Agreed mostly except talking to her..
if you tell her you know the things and ask whats happening
1. will be very hard to catch the reality later..(if there's something)
2.things can go outside your control and you may force her to take quick decision..
3.You wont have any time to think in detail..
better first do some investigation..and be sure of the things..
