My son was 20 months old when I had my daughter, so I remember your pain/frustration! Here's MO
1)enroll your son in a Mom's Day Out for a few hours a couple of times/wk - its amazing how much that will help him and you!
2) a friend gave me some videos and my son loved them. He was just discovering trains at the time, so she gave him some Thomas videos - that helped so much with breastfeeding my daughter. It seemed that every time I'd get her feeding with the great latch, he do something mischevious (sp?) - but we'd watch these together and talk about the trains, the characters, etc while I nursed - it was great!
3) You have to get into a routine with the housework - it won't go away! First thing in the am - unload the diswasher and add dishes all day. Last thing before bed, start it. Repeat EVERY DAY! If you leave dishes in the sink overnight, they become tomorrow's problem - tomorrow has enough in it, you don't need yesterday's junk to add to it! Also, commit to doing ONE load per day from start to finish (meaning: wash, dry, fold, and PUT AWAY). If you can come into the laundry room and put clothes in right away (for me its first thing after we come downstairs), swap them 20 minutes later (while the kids are eating their cereal), fold them (during someone's nap) and put them away (during bedtime routine), trust me it'll feel like you don't spend forever on it, but it gets done. If hubby is home or a friend is over, feel free to do more than one load, but ONE should be the minimum to keep insanity and filth from entering your home. Also, don't leave them in from the day before because then you can't just come in and start them the next day and it'll slow down the routine and either bog you down in stuff to fold, stuff to put away, or stuff to swap and then its a mess again! Other than that, you can just do what you can with the rest of the house as it becomes a priority. I tried to just spend 15 quality, focused minutes on the "big" stuff in the evening after my oldest went to bed and hubby was home to hold the baby - this is when I'd sweep, vaccuum, throw toys back into bins that my son didn't clean up himself (also a great thing to teach!).
4) cook easy - find those ready made meals (for now, this is not a life long plan as you and your husband and kids would weigh a ton) like frozen lasagna, crock pot meals, etc. that you can just stick in the oven or crock pot, pull out, add a salad, and poof - dinner is done. Don't try to do stuff that requires steps, chopping, or prep - the kids won't let you do that!
5) Put on a clean shirt and brush your teeth! Take time for you is what I mean. The better you feel (with no sleep I know), the more you be able to tackle each day. The more you neglect you, the easier it is to neglect the kids, house, chores, etc.
Congratulations and good luck!