Your old landlords weren't obligated to let you in on their plans to sell the property. The new owners are your new landlords, and until they do something that legally justifies your moving out -- such as failing to do necessary and important repairs -- you're stuck with your lease.

It may be of some small comfort to know that the flipside is also true: The new owners have to honor your lease, and cannot boot you out for no reason or raise your rent.