Names: Hayley = cheating friend, Gary = her partner at the time, Zack = the partner's son, and Katy = the other friend in this story.


This happened around 2-3 years ago. I had gotten back in contact with Hayley after a few years of us not seeing each other, and she started telling me about her new boyfriend Gary. Hayley was around 23 at the time, and Gary was in his mid 40's. Gary had a son, Zack, who was a year younger than Hayley, Hayley and Zack had actually gone to the same school together but didn't know it until seeing old school photos.

Things seemed to be going fine in Hayley and Gary's relationship and she ended up moving in with Gary and his family. Quickly Gary's sister didn't like Hayley and was accusing her of doing inappropriate things with Zack while Gary was at work. Hayley denied them and I believed her, just thinking Gary's sister didn't approve of Hayley because of the age gap.

Until one night. Through a series of events I can't talk about because it'll make the post too long, Hayley, Zack and I were spending the night at my friend Katy's house. At night we sorted out our sleeping arrangements, Katy and I were going to sleep in Katy's bed, and Hayley and Zack were going to sleep on the air mattress we'd put up beside Katy's bed. So we turned off the light and hopped into bed.

Katy fell asleep quickly, but I can take hours to fall asleep, but I was quiet, so Hayley and Zack probably assumed I was asleep too. Then I started hearing noises, like hand movements and a male voice groaning. Without getting too into details, it was obvious what I was hearing was Hayley giving Zack a handjob (even found some used toilet paper on the floor the next day, gross). My back was facing them, so I couldn't open my eyes to try and see what was going on, but you could easily tell with just the audio.

The next day we had planned to all go to a birthday party, but I told the others I was feeling sick (I had health problems at the time, so it was believable) and asked Katy to stay behind to look after me, which she did. Once they were gone I told her what had happened, and asked if I should tell Gary. I wasn't close to Gary or anything, but I did have him on Facebook, so I could of contacted him.

Ultimately I felt scared at the potential of losing Hayley as a friend, and not knowing if Gary would believe me since I didn't have any actual evidence, and also didn't want to screw up Gary and Zack's father/son relationship, so I didn't end up saying anything. AITA for not saying anything to him? He and Hayley ended up breaking up sometime last year for unrelated reasons, but I still feel somewhat guilty for keeping my mouth shut about it.

TL;DR: heard friend masturbating her boyfriend's son but didn't end up telling the boyfriend, not sure if I made the right decision or not.