I wanted to expose a cheater so bad?

My ex husband cheated on me through our entire marriage with my best friend. So I have no sympathy for cheaters.

I got a job at a hotel front desk and one thing I was told is you can't give anyone a key who isn't on the reservation, doesn't matter if it's the spouse, unless the person who's that is on the reservation is there we can't give a key. I was also told if someone calls asking if someone is there we can't tell them.

We get a call from a woman looking for a husband and asking if he was there. This specific man was there with another woman. I wanted to tell her so bad and I put the woman on hold and went to my GM and she said I can't say anything. I have to tell her I can't tell her that information. I said "Well as women shouldn't we be looking out for each other?" She told me that out responsibility is to protect our guests and told me a story about how someone came up there to find her husband, they didn't let her have a key and it turns out she was his EX wife, she just kept his last name and has been stalking him for the last year and was a very dangerous person. She also said we have no idea if the person on the phone is his wife or if it's someone crazy out to do harm.

I understand but I honestly had a feeling that's probably not the case. But I need my job so I did what my GM said. I just feel bad that I could have possibly stopped a woman from continuously being cheated on and before anyone says it I know I need therapy to heal from what happened with my ex husband. I just wished I could have saved another woman from pain.