I dont know how should i act with her from now on. she has a boyfriend. what now?

You need to wake up. You were there to serve her needs. Yours do not matter to her in any way shape or form. She will use you whenever you let her if she wants to but you will never get anything in return. She is not sitting around thinking about you, she is living her life. She is very self centered and you need to realize she is not so great. Who needs that? Move on and forget her. You sound like a decent guy and you deserve someone who fills your needs.