Dilemma... Excitment or Nightmare??!

It has been ages. She married. A friend's sister. A total stranger whom have not met. She did mailed me her pictures. There is a thing going on between us but stopped before anything dreadful happen to both of us. So we stopped and make it clear to each other.

Last few days ago, went south for an appointment. Not sure who to call for lunch. Called but no one. Knew I should not have called her. But I thought we were just friends and had make it crystal clear. She called back in the late evening. Nothing much. Nothing unusual. Just a normal chat, trying to catch up each other's life. Happy and all seems normal.

Today, she called again. Was resting on my bed, falling asleep. Took me by surprise. She was horny and slutty while over the phone. Kept smsing after the call. Hopefully nothing will happen due to this. Can't concentrate. Many thoughts running in the head. To be or not to be? Not sure it whether right or wrong. Half of it felt excited with the cheap thrill, another half felt uneasy and dirty.

So now in a dilemma. Advices, anyone?