Have you ever been the 'other woman?"

I've seen several post where people talk about the "other woman" or have been "the other woman" just curious at how many people have been. I, not knowing for a while, was the other woman. Me and my former manager talked about getting a place together, havin a family. But I always wondered why we had to be a secret. Then I realized he was married when his wife came to sit at my table (I was a waitress). It broke my heart. I wanted to end things with him. He met my mother, my child, my family. It carried on for maybe 2 more months, then I realized he wasn't leaving her. I was just a side chick to him. Just curious if any of you ladies have been in similar situations.