Yes that is your crankshaft. What you can try to do to maybe save it is get the nut and grears off and run a die down the threads i dont remember the thread size right off hand. If you dont feel comfortable doing it take it to a local machine shop they should be able to help you.
guy i bought the bottom end from is sending me another one thank god. i thought i was gonna have to put wifes blaster on hold for a while even tho its supposed to be running in a week lol im broke as a joke from all the stuff i already got for it.