Ex crush going out with friend

So i have a bf but I liked this boy before I was with my bf. So I really liked this boy but I failed and made a big embarrassment out of myself. But one of my class mates helped me. The only problem is that she is now dating him. But I feel like a still have a little bit of a feeling for him. Do I tell her or do I just wait. I mean I'm happy for her but I feel like why couldn't I have done that,