Re: Wife does not see this as bad
You were both broken up for 3 months. You were not married at that time. Did you date or have sex with any women during that time?
Did the two of your set down rules for this break up that the TWO of you were to NOT DATE others or anything - ever or for 12 months?
A lot of people date within their circle... it's quite normal.
If she had sex with this friend WHILE you both we talking about getting back together - then that would be an issue. But in reality, she was not yours nor were you her's. What right would you have had BACK then about who she dated, kissed or had sex with? If its 25+ years of no cheating... then grow up and let it go. Go see a therapist by yourself and as a couple to sort this out.
I can kind of see both sides of the coin, we recently had a similar story last month - except it was a few months after and no marriage. That OP (a woman) had sex with a previous BF, while she was broken up with future fiancee - like a year of not being together. Her BF found out about it and had sex with her friend for revenge. Then attacked her for "cheating on him" - he was having an affair with her friend because it was ongoing - while what she did, it was a ONS with an ex and being back in a relationship with her BF wasn't even a blimp on the radar. She and most of us here - recommended that she leave him. Since he was immature and had sex several times with the other woman, even the day before he flew across the country to live with her.
Your wife didn't cheat on you. It was kind of none of your business. I doubt anyone is laughing at you or care, it was 25 years ago. Mature people don't worry about such things. When I broke up with my wife for a few months - I was dating and having sex with others. When we decided to get back together, I finished off 2 last dates and that was that. No more.
I've been in a situation of your buddy many years ago, before getting married myself. She was a FWB woman but had spent about 2 years separated from her husband who WAS having sex with other women. We partied and other mutual friends know we were sexual. When she and her husband went back together about 7 years ago, I never attempted to have sex with her again. We are friends, yes. Her husband knows me. Since she and her husband have reconciled - she never asked me for sex, and I never offered. We're all past that, it's the past.
Supporting those who want to divorce or reconcile. Not every relationship is the same.