it depends ladies and gentlemen.. I have an ex and two of them are my friends and one of them is my best friend. It depends on the situation that both of you and your ex has. If you had communication even after the break up and as long as the both of you moved on. Actually me and my ex (who is currently my best friend) had lots of stuff we share and most of all we give advices when we have heart problems... It's good to know that he and I are still friends. Communication can make the both of you remain as friends. But if you decided yourself to totally forget him/her, well it's your choice..