It’s over

Over a month ago I posted here saying that I kissed someone I wanted to kiss for a long time. We had a nice relationship, kissed a lot more times, had good memories with her. But I didn’t want to put a name on our relationship. Last week I learned that she was writing to boys and flirting with them. Completely wrecked me over. She was my first “successful” crush. I don’t know how to deal with this, can’t even look at her face.