Being in love is a wonderful thing, a feeling that consumes your every move and thought.
I know you were unhappily married, however, and deprived of these feelings for a long time. This may be why you feel you're obsessing right now, and have fears of whether or not it's real.
I recommend trying to relax. Enjoy your time together and try calming yourself when you are alone. Recognizing you are obsessing is not a good feeling (believe me, I KNOW!!!). If you reveal this to her, you may scare her!
Patty