Lily, whats wrong with allowing things to progress?
You've found an awesome person that you love spending time with, the two of you get along well and have seen each other through some harder times in life.
There are some people who are married for Godsake that can't even say that!
Don't freak out here girl, breathe........ he is STILL your friend that hasn't changed.
Let things progress, see where it goes. If you don't I think you will kick yourself in the ass later on