Obviously you will have to replace the headgasket. Depending on the engine type and configuration, it may be a major process. Once the head has been removed you should take it to a machine shop to...
Usually bearing damage occurs when there is coolant in the oil. However, if you flush it with new oil within the week pull off the head and replace the gasket, you should be okay. Basically, you need...
Headgaskets most commonly blow due to the engine becoming too hot, this may mean a blocked radiator or a water leak causing the water level in the engine to drop.
It doesn't necessarily mean a bad engine but with this mileage, you might as well go for a rebuild since if you just do the head it porbably will start using oil.