Help! Just barely hanging on!

I am a single mom, of two great kids 6 & 8, in my 1st semester of the ADN program. I am looking for part time employment, but I haven't found anything that works around my schedule and my children. I have been divorced for 4 years, but I do live with my boyfriend of 3 years.
I have always been an A or AB student and able to handle whatever came my way, but now it's all I can do to keep up and I stay stressed to the max! I love nursing and this is what I've always wanted to do and I understand the material. But on my Fundamentals tests, I seem to stay somewhere between a 76 and an 88, which I have to have an 80 to pass. My boyfriend has always been supportive but since his work has diminished and I've started the program, he doesn't understand my lack of time for him or housework and stays aggravated with me. I don't have time to spend quality time with my kids other than "mom duties" like baths, homework, etc. I get up in the AM, take the kids to school, I go to school, get out of school, p/u kids from daycare, do the daily duties (kids homework, baths supper, etc) and by the time I get that done its 10pm and then it's time for my boyfriend to vent about his day or problems (if it hasn't already started-not to mention drilling me b/c I don't have time or energy to spend w/ him or his "needs") and its 11 or later b/f I can start studying & by then I'm exhausted and absorb nothing & usually fall asleep in my books about 1 or 2 AM. Then on my clinical day, I'm always running late getting my assessment & documentation done, because I was told that I'm too nice and my patients take advantage. Really, I'm just trying to take care of their needs, because I know what it's like to be a patient and I don't want to be rude, but I got fussed at this past week for "time management" b/c my patient was going to surgery and I kept getting interrupted everytime I started my assessment. My midterm clinical review was great and the only bad thing was "time management". I'm beginning to just stay upset and discouraged, just barely keeping up and getting nothing accomplished or done good enough. I'm struggling in school, my boyfriend asks if I'm the only one that neglects their family and responsibilities and has no life, and I just don't know what to do anymore. I want this so bad, but I feel like I am just banging my head against the wall most days. Help!!!