Some good advice here and a lot of bad advice as well.
Sights are for target shooting period.
Have your wife take a threat focused class and teach her how to point shoot.
You will not have time to raise your gun and aim in an SD situation. It will simply be draw and fire.
If one cannot hit a body sized target within 20ft without using sights than I say get more ammo and go back to the range.
Here is an example of what can be done with enough training. $600 on red dot sights or lasers or any other gizmos will get you killed. Just learn how to shoot, low ready, half hip, 3/4 hip AND on the move.
As goofy as his Gopro helmet makes him look this man is very well respected in his field and has been training folks from all walks and depts for decades. He is an acquaintance of mine in Az. His favorite training pistol is a 1911 with NO sights, just a smooth slide.
Practice practice practice. Your reaction needs to be reflexive and instant without thought.