Feeling down

I dropped my class today.
I was too far behind to catch up in the next two weeks. I could not focus on the readings, so I put them off. I could not focus on the assignments, so I put them off. I was so excited and felt such accomplishment when I completed the Associates degree, I thought my life was going to change, FINALLY. It didn't. At first I was so excited to start my classes toward the Bachelor's degree and now, I don't even think it matters.
I'm just so depressed right now. It sucks.
I wonder if I am just destined to be stuck in this place. It sucks. I just feel so miserable and like I have failed.
I have been crabby with everyone lately. I have been angry with my kids about so many things in the last week. I worry that the memories they will have will be of me being angry and not the good times that we have. But, more and more, there have been less good times and more aggravation and anger. I feel frustrated that my kids do not listen to me. Dustin tries to say and do whatever he wants, with no regard for what I tell him or ask him to do or not to say. He has anger issues and I know that his father has a temper and apparently I do too. Myles has a smart mouth. He also completely ignores what I tell him to do. I tell him to hang up his clothes, he goes to his room, comes out like he did it and an hour or two later, I go in his room and there are the clothes I told him to put away! It infuriates me! Luke picks up their habits and obviously only thinks that he has to behave when we are with his Dad. Is it me? Am I doing something wrong? I must be. I feel like a bad mother because my kids do not listen and I yell at them. I feel like I spend all my time yelling at them and not enjoying the time that we are together.
I just am not in a good place right now. I feel like I am stuck here and there is nothing that I can so to change the situation. I do realize that things are not going to change without some action from me, but what am I supposed to do? I don't know. And I hate that I don't know.
I have not been able to find a thing to be happy about. I am stressed on so many levels, I want to crawl in bed and wait for time to me pass by.
I just am not happy and I don't know how to fix it.