Move On: Literally
For cohabitating couples, the days following a cancelled wedding are where it really gets ugly. Obviously, someone's going to have to vacate the premises, but it's not always clear-cut as to who that person should be. For example, let's say the groom called off the wedding. In theory, he should be forced out of the abode and into a hotel, but if the property is in his name, he has every legal right to stay.
Whatever the scenario, make an effort to physically move on as quickly as possible, rather than crashing in the guest room indefinitely. Sticking around will only prolong the inevitable and make it that much harder to let go. If you're hesitant to jump into signing a lease right away, fill up a storage unit with your stuff and shack up with a friend or family member for the time being. You'll probably need the company for awhile, anyway, as you work through your post break-up issues.