Buddies Girlfriend gets tricked at gloryhole

I was alone with buddies gf while he went to the store. We were fucking around talking about porn and I told her I was in to glory holes. She though it was hot, so I looked around our area until I found one then brought it up in a conversation some days later. She wanted to try it out so one day when both our spouses were working I took her in. I told here that I would keep watch outside the door to protect her while she went into the booth, but I went in. I never told her but she sucked me off and I came in her mouth. I was #3 out of 7 cocks she sucked that night. She got a little weirded out that night and gets uncomfortable when we talk about it. I havent really even been able to be alone with her again ever since. As far as I know, she just thinks what she did was too slutty, she doesn't know that I was one of the cocks she sucked, but I still think about it all the time. I can still get hard and jack off when I think about that night.