Summarize:

Dealing with ex-friends and lovers is maybe the hardest relationship to manage, harder than obnoxious relatives and co-workers by far. This is because of the intense bond that you once shared and, in some cases, the bitter end to that bond. One way to deal with seeing him is to develop a script and to stick to it.  If you anticipate meeting an ex-friend or lover, know what you want to say ahead of time. Pick out topics of conversation and know which subjects to avoid. Be prepared. Having something in mind will allow you to keep your cool, and also to avoid coming off as aloof or defensive. There are a lot of potential flash-points in relationships after a breakup. If you meet your ex, know what topics to avoid with him. Don’t dredge up old arguments or resentments, like his new friends that you blame for growing apart.  Try to avoid other obviously tense situations. Meeting your ex-boyfriend in the presence of his new girlfriend is probably a bad idea, for example. Some tense situations can’t be avoided. For instance, you may need to pick up clothes or items that you left at your ex-friend’s apartment. In such a case, prepare yourself beforehand. Be ready to get in, get out, and keep conversation to a necessary minimum. Whether friend or lover, a breakup is like a divorce on a small scale. Your life together gets divided and those around you – friends and family members – feel pressured to take sides. Letting these people to stay neutral can go a long way toward maintaining civility between you and your ex, however.   Accept the fact that your current friends or family may choose to maintain a relationship with your ex, and don’t resent them for it or make them feel badly. Bad-mouthing your ex-friend or lover will often worsen the situation. If you don’t have anything kind to say about him, keep silent or vent to a friend who is at arm’s length. Try to get along with your ex if you can’t cut off the relationship entirely, if, for example, you have a shared business or children together. Keep your feelings secondary to business or family and remember that you need to maintain some civility.  Put common ground first. Whether a business, children, or other reason, keep your priorities front and center in your interactions. A little distance is OK. You don’t need to be best buddies with your ex. Putting some space between you and him may actually be a good idea and prevent future conflict.
Develop a script. Avoid sensitive situations or topics. Don’t force others to take sides. Make an effort where effort is due.