Its pretty safe. Its a lot like a revolver, youll need to pull that trigger a long distance over a heavy load to discharge it. It won't go off by just touching it, dropping it, or even pulling on the trigger a bit. You have to pull it like you MEAN it. Handling the gun according to the NRA recommended practices (keeping your finger off the trigger, keeping it pointed in a safe direction being the 2 key ones here) will be perfectly safe.
That said if you still do not trust it, there are even heavier pull guns out there. The Hungarian FEG 9x18 has a trigger than a gorilla cannot pull. The larger kel tecs are tougher; I cannot pull the p-11 and I am a grown man (with some hand problems, but still).
There is a happy medium here. At some point the trigger becomes too stout to shoot rapidly as is required in most defense situations. Past that, it becomes unusable by all but the strongest people, which generally do not include the elderly, many women, and quite a few men who did not choose plumbing or construction or bodybuilding etc as a career.
The gun you buy just might end up in your wife's hands in a situation. IMO she needs to take it out and shoot it with you, and to feel comfortable both while using it and when it is stored. She needs to understand what it takes to make it fire, and decide if that is enough to prevent accidents.