I'm 58 and told my shoulder joint cartilege is worn away and I need shoulder replacement. Is living with the pain and deferring surgery an option?

Always an option. Not having surgery is always an option; it just may not be the best option. I advise my patients to list the pluses and minuses of each option, then "weight" the options giving more "weight" to this pluses and minuses that are particularly important. Seeking another opinion can also be helpful.
Of course. Everyone has a different pain threshold and differing coping styles with chronic pain. I would say that no one has to have a shoulder replacement however it may make quality of life better. Only you can decide if this is the right move for you.