If I [25F] knowingly had an affair with him [28M] is it a good idea to tell his gf that he cheated on her?

So he was reckless enough to give me his Snapchat username online which is his full real name :/ one search and his profile on facebooks pops up Witt some Photos that his gf tagged him in so I could find her Instagram which is public and his Instagram which is public too. He also sent me a friend request on Instagram where he is tagged in tons of photos be his gf. When I asked there’s so many photos, he said “ignore that” I’ll send you awesome biking posts :/ He knows that she is financially dependent on him and lives in his house so basically she has nowhere else to go now especially after she cheated on him in 2018 herself. So he is either cheating As a revenge affair or she genuinely is low libido which he told me since he was absolutely inexperienced in bed

/r/relationship_advice Thread Parent