It is possible that she may have been opportunistic while in a relationship with you. She may also have been experimenting with her sexuality/life style.
She could also be bisexual or bicurious. Her words to you though would not be excused by any of the reasons behind her behavior.
She may have gone by your work out of curiosity or to antagonize you or for attention from you. Behavior is always purposeful and the purpose is not always clearly defined.
Even though you still have feelings for her, she does not seem as someone trustworthy.There is no need for people to be spiteful once they separate. She had even hurt you after the separation.
You may not have yet met the next love of your life. Unless you are ok with her abusive behavior, you would be happier with time. You've got to respect yourself in order for others to respect you. She had walked over your emotions. Why not allow yourself some happiness despite the situation?