I understand your fear. I myself have issues with a "good man" and trust issues beyond your imagination! Falling for someone is scary because you have no idea what to expect, or what will happen. It's out of your control and that is unsetteling to think about.
I'm a great relationship right now but there are moments when I think that "being single is so much easier." Pain is not fun. And it's so easy to get hurt when you feel something for another person.
BUT... we will never experience anything great without some risk. Love (not that you're in love yet.. ) is just as amazing as it is scary. You have to take the risk of possibly getting hurt in order to get to the amazing part.
The question is.. is this guy (any guy, or girl) worth the risk?
Try to relax. Let things happen as they happen. Try not to stress over what could be, and just enjoy what is.
Take a deep breath in.... now exhale! Be calm. Life is too short to be so worried all the time. Enjoy things while you can!