What I don't understand is how come going out with her has suddenly become hard. You were old friends before, right? You went out a lot before, right? Is the only reason you're suddenly feeling apprehensive is you've realized you might be falling in love with her and you're afraid how she feels?
I think you definitely have to see her again even on a casual basis. Forget 'dates'... just be with her. And definitely a good thing you told her the truth!