To answer the first question, you can’t convince your wife of anything, (you should know that if you’re married 🙂
you can tell her why you want it and if she agrees fine, if not give it up.
If she lets you get one, you need an electric safe, so you have easy access, no lock on trigger, that would defeat the purpose, the gun should be loaded but no round in the chamber, and you must practice every so often!!
if you live in NYC you will go to jail if you don’t follow the rules 100%.
Don’t even think of getting one unless you’re ready to shoot and kill someone, otherwise the bad guy will use it on you, don’t give the wife the combo unless she takes some lessons.
This advice comes from experience I own a few of them (started after 9-11)
ps those that talk of bitachon, you’re all nuts in Germany the ones that died were armed with bitachon, but that doesn’t mean everyone should run and get a gun.