A lot of good advice here but my first suggestion is to find a reputable gun store and let them show you a selection of guns.
The last thing I would suggest is a semi auto, many people cannot load or clear due to the heavy spring that hold the slide closed. The other reason is that there are controls on an auto, slide release and safety that you must remember if you need to use it.
A revolver is easy to load, unload and if you have a failure to fire you just pull the trigger again.
Sagamore has a very good point. Many gun stores that have ranges will also have rental guns. If you take a simple shooters course that many of them offer you will be able to shoot several guns they have on hand.
Also look for a shooting clubs, there are many of them that if you join will also offer courses.
The big thing here is that you need to purchase a gun that both you and your wife need to be able to shoot, load and unload safely.
"The difference between stupidity and genius is that genius has its limits" Albert Einstine