For your wife, whom I must presume has has little handgun experience as yourself, get a revolver. A Smith and Wesson K-frame in 38 special. She will be able to learn to shoot it most easily, and it will be safe for her. K- frames fit a woman's hand just fine too.
If you attempt to force some high powered caliber on her and she is not going to become a dedicated shooter, you are making a big mistake. Give her something that she can use when and if she needs it.