I caught my friend's bf on a dating app

This happened years ago (around 2020-22?) and up until now di ko parin nasasabi sa friend ko na nakita ko profile ng bf niya sa dating app. Me and my friend are friends for years and yung bf niya naging classmate namin nung hs (that's when they got together, graduate na kami ng college now). I've been on the dating app for quite some time and gulat nalang ako na andun bf niya, real name and pictures. I'm friends with the guy naman pero I don't want to confront either of them, I don't want to mingle.

I think of it from time to time na sabihin sa friend ko or even ask the guy kung may nagpoposer sakanya kaya siya may profile. They've been together for years na rin (even then nung nakita ko profile niya) kaya if I bring this up, baka ako pa sisihin sa drama/break-up nila.(wag naman sana, and no it's not in my hands na magbreak sila so shut up nalang tayo)

I can't really tell this to anyone bc this is a small town (baka kumalat, again ayokong ako ang sisihin) and I've been their third wheel for years na rin and masasabi ko namang masaya and maayos rs nila to the point na nagplaplano na sila magpakasal kaya baka may naninira lang talagang iba.

She's been a good friend to me and ayoko rin mahurt siya. Nasasagi lang talaga sa utak ko na it's her right to know din (their right kung poser man) and at this point, it's been so long na parang water under the bridge nalang yung issue(...???) pero what if totoong siya yun diba? Tas nalaman pa ng friend ko sa iba? Edi ako pa makokonsensya na di ko nasabi agad but I'll take the L.

I just got back on the dating app recently and di ko na nakikita profile niya kaya baka poser nga or something but I don't know if I'm being a bad friend for not telling or being a good friend bc I don't want to hurt her and her own rs. But right now it's my own little secret.