Is it normal that my mother can't get along.

My Dad loves my mom and does everything for her, even when she acts like she doesn't want him to. My mom started abusing this a while back, and at this point does almost nothing, getting up at noon to take care of my 2 year old brother for a few hours until I get home (then she goes to bed), and I get to take care of him for several hours, fitting my homework time into that time. Afterwards my Dad gets home from work -- which is an hour's drive away -- tired and wanting to rest. Often my Mom gets mad at him for reasons only she knows about, and often has him go back out to get something she could have gotten out of bed to do herself. During the time I'm at school she tends to go out and spend money in big gulps, like it's a habit to waste money on herself. She also claims to pay the bills but then doesn't, so that we go without warm water or TV for a while, and end up paying a greater fee. She complains alot but never does anything about it, and this all really stresses my Dad out, which in turn really stresses me out. I finally decided to post this when she yelled about never doing anything for me again for being "disrespectful," which upset me because I didn't DO anything disrespectful.
Thanks for any input, I feel better just getting this off of my chest.