The frame is still rideable. You just need to replace the fork. I am pretty sure that the Vitus frames are french thread.

Get a new fork and you should be fine. Tange makes a nice looking chrome replacement fork for not that much. Or you could seek out a used one. There is a buckle in the top tube but that doesn't mean it will self destruct on you.

The joy of steel is that you can ride cosmetic blunders, unlike carbon fiber. Your frame is not garbage.