I am new here, but I wanted to post and tell you that I feel your pain ^_^
I am 34 with two small ones (seven and two), with a 12 credit class load and having a part-time job to keep things covered, so I understand where you're coming from! For awhile I took as many classes online so I could spend the extra time with my then newborn son, but as he's gotten older I've had to go back to a full-time on campus schedule. It was difficult at first but then I realized that not everything needs to be ***-n-span in the house, and so long as most of my kids' meals are healthy, the occasional happy meal wont kill them 
My seven year old understands the pressures I'm under, to an extent, because I try to take her to may classes at least once per term (usually I'm in classes five days a week, so her school closures usually allow for at least one day per term) so she can see what I'm doing and how it's similar/different from what she's doing in her own class. Its a great way for us to bond and for her to get a positive image of how college works. That way when its her turn she'll already know the efforts involved in the process.
I'll eventually be pursuing a PhD and going into post-secondary education, so I have a lot of school ahead of me. The most important thing for me is to understand that the house doesn't have to be perfect, and if you spend more time with your family than with the laundry you'll be FAR happier in the end ;) Our weekend trip to the local buffet helps as a pressure valve with kitchen stress too, and there's definitely something to be said for one-pot meals. We eat more rice in a week than most families do in a month! So long as they get their colors (we eat foods that have the whole rainbow represented for vitamins and minerals) they're happy, and so long as we're together, its all good :D
Hope this helps, feel free to contact me anytime if you need someone to talk with, vent, etc etc :)
Ali