Many mothers have walked in your shoes. The fact of the matter is that it is very very hard to juggle it all. It is extremely stressful, but if you are going to commit to a course of study, you are going to have to make compromises. You absolutely will not be able to spend the same amount of quality time with your kids as other SAHMs you know.
You study when they nap, you study after they go to bed, you grab an hour when the toddler is watching an educational video or program. You grab an hour when your husband is home. You have day care or home care or whatever is dependable and safe. You listen to lectures in the car if you can. You make flashcards and use them any minute you get a chance: waiting at the bank or pediatrician's office or the dry cleaners. Every spare minute is spent on school work. You maximize the weekends and hubby just has to deal with the fact that you are no longer available for couple time as you once were. This is a sacrifice.
Plan on feeling the stress to your relationship, guilt feelings that come with having to tell your kid "sorry, honey, mommy has to study," etc.
All that said, it's 2 or 3 years of your life. You will all get through it, and the kids will get over it if you can't attend to their every desire 24/7. At the end of it, you have a career.
Oh, and then the real sacrifices start...