Should I tell her I almost slept with her boyfriend in an orgy situation?

So listen, it was summer after senior year. I was a thirsty bitch/hoe/slut. I know who I am. I was on Grindr looking for “fun”. This guy popped up. We will call him Mark. Mark and I talked for a while. We exchanged pics. I asked him about how his girlfriend would feel. He freaked out. Blocked me. But not before I took screenshots of his nudes pics and convo. He was telling me about this group sex ring he wanted me to join and all this shit. Anyway I hit him up on facebook. And his girlfriend followed up with me about it. She asked me what the fuck I was doing when hitting him up? I never answered the text. I never told.As it turns out, after two more years of dating (for a total of like 5 years or something like that), she walked in on him having gay sex. He was gay.Should I have told her??? Should I tell her now???? Any general advice???