Betrayal

Please if you are going to judge and say mean comments don't comment.

Over the last few months, I've made a friend online. We would often ***, but also talk about personal subject. I've discovered today he has a partner and has been with that partner before we started talking. I feel dirty, betrayed and hurt. We've bonded on communication and honesty, and now I don't know who to trust. I really felt like they understood who I was and cared for me.

Any tips or reassuring words? Am I alone in this situation? What should I do?