Hello there fellow Baltimorian!
It's good to vent, so do it as often as possible...Once we decide to have children, we sign up for a lifetime of care giving. Yes, a lifetime. Our toughest challenges are also our most rewarding. Loosing yourself in the process, however, is NOT a good thing. You said you had 2 boys? Is your youngest 3 years old, or is that your oldest? Whatever the case, you might want to think about putting your 3 year old in pre-school (if he isn't already going). For 3 hours a day he will be interacting with other kids his age, learning fun stuff, and maturing. You can also implement some of the same activities from pre-school in your home, keeping his day consistent and structured.
As for your younger son, sign up for some mommy and me classes. This will allow him to socialize with other people besides his family and stimulate him in a way that will allow him to be calm, and increase his maturity rate, therefore making your life easier.
Now, for the most important thing to consider: YOU! If mom is unhappy, whatever the reason, the rest of the family will feel/know it. Go shopping, have a pedi/mani, have a girls' night out, have a shot of tequila! You're absolutely correct when you say that being a mom is the hardest job on earth, no doubt it is! And it's also the most unappreciated job on earth, but keep this in mind...without you, the world stops! Take care of yourself, you're a great mom, a little burnt out, right now, but that IS normal. Even if you didn't have kids and just worked outside of the house, at some point, you'd get burnt out doing that too. No human on this planet can keep going at 100 mph without burning out, the trick is to remember it's OK to feel that way, and to find a way to re-energize. When I burn out, I go to NYC to "plug in" and fill myself up with that undeniable energy, get my butt back to Baltimore and get back to business.
You're the BEST, don't loose sight of that!