Make a new plan. Nursing school is very frustrating and requires lots of dedication but it can be done. I have four children, ranging in ages from 4-16 and am one semester away from finishing. I was in your same shoes, feeling guilty for not spending more time with the family but wanting more for them at the same time. It's a very difficult adjustment to make but know that it's not forever and it really does go by very quickly. So my advice is to change up your game plan. It's very important to get your house in order first, so stock up on stouffers frozen foods and teach the kids to pick up after themselves and do their own laundry. It's a help even if it's not perfect.
This is what I did to tackle the material: I made sure that I read every word in the chapter, did the study guide, and got a couple of nclex books to try and figure this thing out. Fundamentals success helped me pass the first semester and helped me to understand what to look for and why. Make sure that you are thinking though the concepts. Now this is not memorization, this is understanding. Be able to explain to someone else what's going on and why.
As far as study time is concerned, you need to study everyday, so if you have little ones either put them in daycare 1/2 day or arrange alone time because it's impossible to do with too many distractions. This stuff is hard and you need good chunks of quality study time. If during the day doesn't work for you then try studying at night after they go to bed. The key is periods of quality, quiet study time everyday. I know you get discouraged sometimes, I know I did many many times but once you get a plan that works, it makes things so much easier. Best of luck and don't give up.