Call your OB. They can help you determine how serious this is. While all of what you are feeling can be VERY normal after pregnancy, this might be a little more than normal. You are right to seek counsel, and I think this is the perfect place for it. We can give you our honest opinions without the 'sugarcoating' we sometimes do with our friends in person :).
That being said, you are wise to think about this, and should make an appt. with your OB today. It surely won't hurt. As to breastfeeding, RELAX! Sure, we all know breast milk is awesome. But so is formula for those who need it. Maybe do some of each to take the pressure off? He would still get the benefits of your milk, but you can give yourself a well-deserved break.
Hubby is right that you can't pretend the baby doesn't exist, but maybe he could jump in at bedtime, or some other time, as well if he hasn't already? Don't forget to tell your older one that he is lucky to have a sibling, and the baby is lucky to have him. You will never regret giving him a brother (once you get through this patch :)).
This will get easier, but it is okay to need help, and to get it. Also, the poster who said some of this is tied to sleep deprivation is right! Any way you can get someone to stop by for an hour or two so you can get a nap in? At least do it when hubby is off work for sure! I know it is hard to give yourself those breaks, but please try!
Best wishes.