Can I and should I still persuit this Scorpio ?

I am into this Scorpio guy from my gym. I just herad he's been dating this girl since summer and that she's moving in with him . I guess he's about to get engaged. We always had this chemestry at the gym but nothing ever happened. He is a trainer there and I've been a member on and off since '03. I feel a little sad. Talking to one of his best friends who is my trainer I confessed I had a big crush on him and she looked devastated ( which I thought it was just precious for her to have felt so bad for me LOL )while delivering the big news. He's lived with a girlfriend before that I know of, so I am NOT totally convinced he will marry this one. The question is : Should I still persuit him subtly by letting my trainer let him know about my real feelings now ? I know she will say something. He's her friend more than i am hers... Would he care as a Scorpio ? What should I do ? Leave the doors open or not ?