Whats a MOM to do!!

This is a question for all you stay at home MOM'S out there. I'm starting to realize my life of really working is about to start. My neice once made fun of me and that I only worked 2 days a week and I informed her no i work 150 hours a week and take 18 hours a week and go sit behind a desk and breath. And now with not having those 18 hours to relax and breath not sure what I will do. I'm not sure I am going to be cabable of dealing with the kids everyday. How do you all do it? I've decided I'm not very patient and I'm pretty demanding. (LOL Now I know where Carter gets it from) So any suggestions to keeping my sanity and enjoying my time home with the little ones. I realize it's going to be super hard being home with 3 little ones and luckily Camden does has preschool 2 days a week, but I'm not really worried about him. Carter is going to be my struggle child and I can already tell he is not going to like this new baby. Sure he will think he is cute for the first 10 minutes, but he is not going to be happy with his new brother taking all of his mom's time. And heck if all I had to do was sit with my 3 kids and play and enjoy them then great, but we all know all moms have a million things to do during the day. So looking for ideas on how to deal with them and keep the sanity.