Everyone has an opinion on this subject, mostly because everyone has an ex. Some people tend to friends with their exes, while others have little or no relationship with them.
There’s no real right answer when it comes to what’s healthy. It’s not necessarily a sign of someone’s healthy ego if that person is friends with his or her exes. That person could simply have a hard time closing the door and may need to keep his or exes around. On the other hand, it can be very healthy if you view your ex has a friend and there are no residual issues left over from your romantic relationship.
It’s the last point that hangs most people up from maintaining a friendship with their ex. Often there is anger or resentment that clouds the picture, and people often do better moving on and learning from the mistakes they made in their last relationship.
If you want to maintain a friendship with your ex, you must be dreadfully honest with yourself. You must feel confident that you have buried any resentments, that you no longer have any sexual or romantic feelings, and that your current or future partner wouldn’t feel threatened by the friendship. This is a tall order and the very reason why most people aren’t friends with their exes.