Mindset is primary. The best primer I know of to develop a proper mindset is Cooper's
Principles of Personal Defense - this has been a standard reference for decades now. See
http://www.paladin-press.com/product/Principles_of_Personal_Defense/Other_Combat_Shooting to order, it's the best $20 you'll ever spend on personal defense IMHO.
Then, refer your DW to Kathy Jackson's website called Cornered Cat -
http://www.corneredcat.com/ . It's an armed self defense site written by a woman for other women, and it has been helpful to a lot of people I have referred to it. There's a good section there on Mindset - see the Contents tab to find it, or see
http://www.corneredcat.com/Like_a_Cornered_Cat/ to get started.
It's good she was able to control that situation without using violence - but she really should have been FULLY READY, WILLING AND ABLE to use whatever level of violence was necessary to protect herself, had her initial efforts to 'talk down' the situation failed. What would she have been able to do in this case had she faced a genuine, determined attacker? That IMHO is the important question that needs to be addressed. And that question is one primarily of Mindset, as I see it. All else follows Mindset.
She is a priceless individual - many folks fail to view themselves properly in this regard IMHO. It may be a self-esteem issue, I don't know, I'm no psychologist and don't even play one on teevee. But whatever the reason is, she needs to know that she is one of your family's most valuable assets, and she needs to be just as willing and able to protect herself - for her own sake as well as yours - as you are to protect her.
As a follow-up, take a look at the NRA's Personal Protection In The Home class. For a description and class locator, see
http://www.nrainstructors.org/searchcourse.aspx . Look into other basic classes from the NRA as well. It seems to me that a certain number of people, women in particular, have a serious level of doubt about their own ability to defend themselves effectively with a firearm. For some of them at least, learning how to shoot defensively can help a number of those people overcome this self-doubt. It seems to me that for some people, "the skill engenders the will" - once they learn they CAN shoot effectively and safely, all of a sudden they realize that they CAN defend themselves. Again, this may not be the issue in your DW's case, I don't know, but it might be something that would help. Having a good home defense plan in place, developed for your own family and house, discussed and practiced in your home, might be a help in her knowing what to do should a similar situation present itself again. Just as your family needs a fire evacuation plan and plans to cope effectively with any other emergency, you need a home defense plan and also need to drill/practice it so it can be carried out under pressure.