with my friend's ex-wife?

My friend and his ex wife have been divorced and have gone thier seperate ways for over 5 years. I had run into Cindy at a community function and we kind of hung around that night. Since then, we have gotten close, found out we enjoy many of the same things, and we get along pretty good. My friend Steve knows nothing about my talking to Cindy, and I am not sure what he would say. I should also add that Cindy and I are both currently single, my friend Steve has been living with his girlfriend for a while now. What should I do? It is like a perfect connection with the way wrong woman. Thanks.