That you and I 'need' a car is sadly part of the great ongoing con. :c/
Genuinely very sorry for the loss of your engine. Are you sure the mechanic isn't trumping up the damages? Have you checked online forums to see if that kind of damage is even possible from a belt?
Yeah... cars and their noises need to be tended too sooner rather than later. Otherwise pain and expenses ensue. ¬_¬