When the absolute last thing we want to do is rehash what happened and jump into something new, how do we navigate this social mine-field without alienating people and coming across like a hot mess when we freak out when asked one question too many?
1) Keep your cool. Even though it royally sucks to have to field questions about what happened (especially when you JUST managed to not think about your ex every five minutes), most of the people you ask said questions mean well and care about you. Plaster a smile on your face, assure them you're fine and that things just "didn't work out."
2) Change the subject. When dealing with a socially sensitive questioner, sometimes a simple change of subject can be enough to dissuade any further discussion on the topic: "Nope - I'm not really dating anyone special. So - how about that game last night?"
3) Control the conversation. Even though the questions are directed at you, an easy trick to deflect the attention and move into new (less annoying and painful) territory is to give a short answer to their question, and then turn the questions on them: "I'm doing great, thanks - and how are you and Robert doing? Where are you going on vacation this year?" Hopefully they'll be so distracted talking about their vacation plans, they'll forget to focus on you.
4) If they persist, be firm. Your break-up is no one's business but yours, and you are perfectly within your right to not talk about it if you don't want to. When dealing with a more pushy questioner who won't drop the subject, despite your attempts to talk about something else, sometimes a firmer hand is required: "I appreciate your concern, but I'd really rather not talk about this anymore. Why don't you tell me about your new project at work?"
5) If all else fails, walk away. Finding an excuse to leave the conversation is a perfectly acceptable response to being grilled about what happened between you and your ex. Simply say "Excuse me, but I just saw my friend walk in the door / need another drink / need to use the bathroom" and bail.
Although the conversations about your well-being will be frequent and numerous at first, they'll mercifully die out quickly as word gets around. There will always be the family members who ask you point blank why you haven't found someone yet over the sweet potatoes at a family dinner, but hopefully those conversational gems are few and far between and can be viewed as humorous rather than bringing up a whole boatload of memories you're trying to bounce back from -- as is the case right after a break-up.