You need to step back and just take a deep breath... It sounds like you are having a panic attack, and just feel completely crushed by the pressure. Is there no one who can help you with your kids? Are you getting any support from their father? It sounds like you need a little break. If you can't, then you just need to let things go. It is ok if your home is a mess. With 3 kids what home wouldn't be, especially if you want them to be happy kids. Don't worry about things that are beyond your control. And don't stress over Christmas ... I am sure they would rather spend time with you than get a ton of presents.
Is there a reason you have stopped treatment? Please do not ignore your depression. You need to take care of yourself so you can be well, and in turn take care of your kids. You have 3 great reasons to fight and live. Your kids need you. You can't blame yourself for everything your kids do... they have free will, and sometimes will not make the right choices. But, you do have the power to react. If you feel they have done something wrong, then correct them. Show them the right way, and the best way to do this is to set the example. Be a good role model for them, and show them that chose life for them. Show them that life is full of struggles but they like you can handle it.
Please don't lose hope, and don't stress. If you need to talk, I am here for you. Good luck