You have to use what you can operate with your osteoporosis and feed with your income, including the required practice. The .22 is fine for a defense handgun, provided you and your wife both have one available for each of you.
If you have a spare brick of .22 around, the two of you should very soon shoot up 250 rounds of it, to familiarize you with the guns you will use, then use the other half of the brick over the next 5 months in a monthly session, one box of 50 split between you.
Be sure and carry them whenever you can, as stated below, Rule No. 1 of Gunfights is to have a gun.