I preach no but I want it...?

So I'm in girl guides, I know it's corny and all but I love it and I love the girls I'm with, they have been my family. Anyway my close friend and I have always preached to the younger girls about abstaining and waiting for the right guy, not trashing your reputation and all that and I really believe in it. So much so that I'm almost 17 and have never been kissed, this guy I know is really into me but also has a gf yet I continuesly allow myself to text him eveyweekend and our conversations turn extremely inapropriate to the point that it is intact ting. Now I know I talk against it but I can't stop myself wanting this guy to actually do the things he tells me... What do I do?