What if HE returned??

What would you do if the love of your past which you have loved for more than 5 years (also the one who makes you shiver when you speak to him - ON THE PHONE) suddenly returns after 6 years? What should you do when you are currently in a relationship with someone else? With the one you want to spend the rest of your life with?

Lets call the past lover (P).

You have loved P most of your life before you met C. However, for some misunderstanding, P left for 6 years to another country and has never kept in touch. After 6 years, P comes back. Brings you to his new-halfly-renovated shop which is like 500 metres away from your home(what does that mean?). Bring you out for lunch. Chat with you for more than 7 hours. Although you don't feel that you were meant to be with him, there is a slight curiousity on what if he did not leave after the misunderstanding, if the misunderstanding was solved in the past, how much would the relationship progress? Why would he come back now after 6 years? Why? What does it mean?