5967 gross
(764) pre-tax savings
(316) pre-tax expenses
(922) taxes
(460) Roth savings
---
3505 remaining
Assume you can at least get post-tax expenses down to 3000 and save the difference
Savings rate = (764+460+3505-3000)/(5967-922) = 34%
Current income-generating assets: 145K
Required amount to retire, in current dollars, at 4% SWR: (3000-915)*300+107K = 733K
Time to financial independence: 16 years
I was a little sloppy with this, but it's pretty close. It doesn't account for your mortgage interest, but that's offset by things like future commuting expenses. Also, once children are in school, your wife might work more. With the current MA law, health care should be cheaper. Odds are better than average that with income increases and reasonable expense reduction, you could retire around age 40.
You can reduce expenses for pets, meals, electricity, and phone and maybe refinance your mortgage to a 15-year, 3%. I'm happy with AIM loan, an online lender, and it sounds like you'd have the 75% LTV to go that route. You can shift your Roth savings to pre-tax (increased by the appropriate amount; at a 15% marginal tax rate, that would be 460/0.85=541). If it's fully in the 15% bracket, that step alone would bring your savings rate up to 36% and reduce your time to FI by almost a year.
If the 70K goes into an investment account, you can still get at it for emergencies. Worst-case, you sell low, but the chances of that are in your favor. Right now, you're losing 3% guaranteed.
It takes a certain counter-cultural outlook to get the Mustachian approach, which includes perspectives like 1) even low-cost American lifestyles are extravagant, 2) dollars should be invested so they work for you, and 3) it's much better to buy time than stuff. Your spouse might never get on board with you financially, so take any progress on her side at all as a huge plus. You've read the blog posts on this topic?
http://www.mrmoneymustache.com/2012/03/22/selling-the-dream-how-to-make-your-spouse-love-frugality/