Some of these suggestions are not taking the original order at hand, and are trying to steer you to a full size, and somewhat heavy handguns for a half size person that is recoil sensitive.
I honestly could not steer you, or her, to the right revolver only because I don't own a 22 revolver, neither do I know much about 22 revolvers, but those NAA could be complicated in a "panic" situation.
The NAA is not a point and shoot gun. It's a pull the hammer, then point and shoot, pull hammer again, point and shoot, now just do that three more times in less than a second.
Somebody mentioned the Walther P22 (22lr), nice size gun for smaller hands, but yet it would fit a larger hand also. You may, or may have not considered a 22lr, but when she (Your wife) can shoot 11 rounds in center mass in about 2 seconds, that would make a formidable SD gun even for the weaker peoples.
And, she will like it!