You'll never see another game again, .....well OK that might be a bit harsh...
If that was my house the kids would need shoes, wall needs painting, car needs fixing, that new coat, vets bills, you get the guilt trip anyway and you'd give up the money if it was in savings ready for the big spend. I had this exact same conversation this time last year, but now she sees what I get from it, the kids love it, it's a fun hobby.
So...my proposal, and one I have dabbled in and done quite nicely from....
Flip the situation, sell the idea as an investment, if you have some basic skills do what every other bugger is going, buy crap cabinets, jamma it up, crappy TFT, 60-1 slam it on ebay = profit, reinvest in your arcade.
You're not hurting anyone, some people will cherish a cabinet with a TFT and a 60-1 - look honey pacman....
It's gonna happen anyway, Mr 60-1 will buy his cabinet anyway, so why not from you. Best money I made was buying a couple of beat up old cabinets and bootleg streetfighter boards, went like shit off a stick, honest cheapo flip that bought me 3 cabs, and the people that got them probably love them to bits.
Just don't hurt any classics along the way, Rush N Attack, Robocop 2 etc...
Do it right, you will have a free arcade, and £1200