Told my ex fiancée’s new BF about her cheating on me.

10 years ago I was engaged to a girl who I worshipped. I gave her and bought her everything. Six weeks before our wedding I found her with one of my so-called “friends.” Turns out she was sleeping with many of my friends and others. Her excuse was I worked too much. Which I did but she shouldn’t have done what she did. I’ve moved on and got therapy etc. so I hardly ever think about her

Fast forward to the weekend when I see her with a guy I have done business with. He’s a good dude and I want to keep doing business with him. I told him about her cheating on me 10 years ago. I didn’t do it out of spite for her but because if she does it him and he finds out her and my past it would jeopardise us doing business. AITA?