Hi A.,
You need support! I have been in school since my oldest son was 9 mos old (he is 4 now). I still have 18 mos to go and I will have my Associates degree in nursing. It can be stressful. I have also worked full time up until now. (I am in clinicals now and have school Mon-Fri)I have to say that going to school now that I am older is a lot easier for me. I have always been a fairly good student, but learning is a little easier now that I can apply it to real life. I have a better perspective. My house is cluttered and not nearly as "clean" as I would like it, my laundry is never really done. I am fortunate to have wonderful parents and in-laws who watch my children while I am in school and my husband works. They also will watch them if I have a big test and just need an afternoon to study. I tried to schedule some time between my classes (as much as I could) to study. It seems that when I am at home I can always find something else that needs to be done (laundry, cleaning, playing) and I put off the studying. Organize. Set a schedule for yourself and stick to it; studying from 10-11pm each night, laundry all day Sat, "husband time" on Sun and Wed evenings ;) whatever works for you. Don't forget to include a little sanity time for yourself though.
Ask for help. If you need someone just to watch your children, maybe your husband to pick up some housework whatever. You can't do it all. You are still being a good wife and mother even if you aren't able to give as much time for those specific things. Bettering yourself by getting an education and doing something important to you will set a good example for your girls. Try not to feel guilty for missing some things in your children's lives. It is hard, but they are still young. They won't remember that you couldn't attend the first preschool field trip (something I cried over), or breakfast with Santa that you have always done (more crying for me). When they are 12 and 16 they won't begrudge you for those small missed things. Just do your best and it will pay off in the end. At least that's what I keep telling myself ;)
Good luck
~L.