Would it be life-saving for me to buy a portable generator to keep my refrigerator and freezer going?

We do not see it is a necessity for you to have this in order to preserve your lives. It would be a blessing in terms of convenience to have a way to continue to use perishable foodstuffs, but the economic trade-off might or might not be worth the cost. So this is something you would need to consider and make a decision.