hey i was wondering if a shot lifter could cause a total meltdown of my motor and if it can...how long would i have before it happens

A shot lifter will make a ticking sound in the motor, it can possibly break the motor, but not beyond repair. I can't say how long it could take for the lifter to completely go, but you will know when it happens, and it should cost you in the neighborhood of $800 including labor and parts to fix. If you replace one lifter you have replace them all.