@diver4life00,
Recognize that childcare is a job unto itself. Forget what happened earlier. According to
Payscale, a childcare worker makes around (at the median) $9.82/hour, and your wife is undoubtedly working off the clock, so it's beyond 8 hours and it includes weekends.
Let's say she works 10 (there's a round number). She could be easily putting in a 70-hour week in childcare, particularly as your children are so young and they probably want Mommy all the time or most of the time. That's $687.40 (no taxes taken out) you are saving every week because she is a stay at home mom.
Also known as $35,744.80 per year because she doesn't get two weeks of vacation like you do.
This is not to say that you do not contribute to childcare. Perhaps you do 100% of the time when you are at home, but she is still putting in 8-10 hours at least Monday through Friday because you are out working or commuting.
So don't say she doesn't work. If she was at a job, you would be paying someone else to do that.
But still sit down and talk. Discuss everyone's expectations, including what will happen when your younger son can go to pre-K or the like. Will your wife be expected to work part-time? Or are you going to want to have another kid? Or something else?
Talk about spending, too. Many, many marriages have fights over money. Have a discussion. Be frank about the bills. Mortgage (or rent), utilities, food, and clothing (for kids who are probably growing out of their clothes pretty fast, and will for a few years) are not really negotiable.
Talk about where you can cut spending, and it may be for things like you taking a lunch or riding the bus, or giving your younger son hand me downs from the elder and picking up some of his clothing at Goodwill or from swaps with other parents if you can swing that. Maybe you can cut cable or drop your landline if you pretty much only use cell phones, and don't get the latest.
Do you have subscriptions you don't really read? Then read them online and ditch the newspaper and magazines which only clutter up your house, anyway.
Switch from soda to water (it's better for everyone, anyway). See if you can make more food from scratch rather than prepared (you might want to invest in a slow cooker; they are awesome for this, very easy to use, and require nearly no attention).
What I am saying is, approach this as a partnership, and that includes acknowledging the very real contribution that childcare is. I am not saying you are 100% in the wrong at all - just don't forget that what she is doing has a real value, too.