Cellisx, when I was in my teens I went through a stage of thinking that if a guy passionately kissed me or put his hand down my pants, then he must be interested in me. How wrong I was! The truth is that if a guy is interested, he will seek out your company by asking you for a date.
You say that you think he's interested in you - but unless you've left out a whole lot of stuff, there's nothing here to suggest that. The ignored FB message just make his lack of interest even more obvious.
Good for you not sleeping with him, you would have ended up as just another notch on his bedpost.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.