Good behaviour is paramount when dealing exes. Revenge tactics or bad-mouthing will only make you look bitter.
When you find love in pastures new, inform your ex of your
liaison - either tell them yourself, or get the grapevine to do it
for you. A status change on Facebook will usually get the gossips
If you move on inappropriately quickly, then hold off from spreading the news until it's a sure thing, and delay going public for a while to avoid any accusations of cross-over.
Remember that an ex's close friends/family are always off-limits.
Group meetings are best when dealing with exes; constant
one-to-ones are never going to look innocent.
If you bump into your ex unexpectedly be polite and cheerful, and if you find the encounter painful, make your excuses and leave.
Don't be flippant or flirt with other people in front of them.
Try to stay in control.
If you wish to maintain good relations with your ex, or even be their friend, you will have to accept and be friendly towards their new partner. Mature good manners are the best policy.
You should be completely honest with your current partner; they will need reassurance that no feelings remain between you and your ex.
Your Partner's Ex
Don't make scathing comments to your current partner about their
ex; you'll only appear insecure. Don't probe your partner for
details about their ex - why do you care anyway?
If you have to meet them, maintain absolute grace and composure.
If their ex is a friend of yours, it can be dangerous territory and you are unlikely to receive forgiveness and quite likely to lose a friend.