Paleobird, sorry to hear about the hassle. Cold footed buyers make me crazy. But then just as you're going to go out and beat up an inanimate object with a baseball bat, in walks a buyer who needs exactly what your home has to offer.
My vote is to move into the apt you like. You got a couple of offers, so it's not like it's an undesirable house. Even if this deal falls through, you'll most likely sell fairly soon. If you can swing the rent on the apt, and any small things that might be needed at the house while it's empty, go for the apt you like. OTOH, if your realtor gives you even an inkling that the two offers were flukes, and it might take a long while to sell, you might want to reconsider.
Do what makes you happy and lets you sleep at night.
"Right is right, even if no one is doing it; wrong is wrong, even if everyone is doing it." - St. Augustine