AITA for exposing a year-long “phantom girlfriend” lie to my close friend, knowing it might destroy his friendship with my ex?

It was all a year ago but I still ask myself if I did the right thing. I’m 19 live in a conservative post-soviet country where the life of LGBTs+ is often undesirable. I’m also in an open marriage with my wife (she was my best friend for many years and at the time this story went down we were friends).

Senior year I had a tight-knit group of friends: me, a girl I’ll call Mary, her biological sister, our mutual friend Alex and one more person. Upon graduation I got in touch with Mary’s sister a lot but suddenly decided I was in love with Mary. It was intense and it caught me off guard. In the fall I told her how I felt and to my surprise she felt the same way. We started seeing each other in secret.

I was not pretending to be a lesbian for everyone on my side: my sister knew, my wife knew. But Mary was terrified. We made a pact that we wouldn’t tell anyone about us in her circle, not even her sister or Alex. I said yes assuming that I was advocating for her peace of mind.

Alex is a great guy. While Mary and I were secretly dating, he came out to me as bisexual and confessed that he was head over heels for Mary. I went out with the girl he loved, and had to look him in the eyes pretending nothing was happening.

I’ve asked Mary a couple of times if we could be honest with him because he’s "one of us" and he would totally get us. She declined. Instead we fabricated something ridiculous: she began telling Alex elaborate stories about a "new girlfriend from college." She was talking about our dates, our intimate moments and sex life – but she replaced me with a fictional character, was some ethereal "girl from beginning of time."

I’m ashamed because I was the one who enabled it by saying "Oh, what a pity, I’m in love with Mary, too but she’s taken!"

Last summer I went to a Christian youth camp (my parent’s are very religious). When I came back I was emotionally exhausted. Mary said two weeks later we need to talk seriously. She said that the chemistry is just not there anymore" and that she wants to break up." I was in pain but I didn’t hold her. We agreed to be friends.

After the breakup. Alex and I became closer than ever true "brofessors." working side by side, I wrote to Mary, "Now that were not together, can I finally tell him the truth?"

She said, "Yes, okay. "

We went with Alex to the lake and when we came back I told everything. At first he laughed, thinking it was some kind of weird joke. But then I told him in detail what happened.

His expression changed from confusion to complete devastation. He wasn’t angry that we were seeing each other. He was devastated that she couldn’t tell him. He felt like a complete fool. And I won’t deny that I did it to make myself feel better, because I needed someone to talk to.

After that, Alex and Mary took a break from talking at Mary’s behest. I remember when Alex came to my house and started crying over it. Right now everything is okayish, I stopped talking to Mary but that’s a different story