[QUOTEbut I know how a good marriage works, been doing it myself for awhile now.][/QUOTE]
So why are you on here asking questions? LOL.
Seriously, be honest, but don't apologize too much because you have a certain amount of duty to be prepared to protect her. Be humble, but don't grovel to her, yet it's important that you have trust, that she knows above all that she can count on what comes out your mouth to be the truth, even if she does not like it.
Tell her that it was too good of a deal to pass up and that it would have cost you significantly more to wait. Some things are like that. Then tell her that it is her turn. Women can smell unfairness a mile away so you need to put her inline for as much as the gun cost you. Tell her that you want to be fair about it and then make it your mission to do it for her. Perhaps even for a little more than the pistol costs. Women feel good when they get the big end of the stick. Give her all the money from your next side job and so forth until she's caught up and equal with you.
and rub her feet. Women are on their feet all day long and love a good foot rub. This will melt away a lot of anger and you can take that to the bank.