HI. I know what it feels like. I hate it too. Some things you can do is fight it with " helpful thinking" and activity.
Your not worthless. For one, you love your kids and that is worth a billion. This is one big "worth it." You have to think of all the smaller things that also make you WORTH IT.
You say you want to sleep all day. DON'T sleep all day! It is known (shown in many scientific articles) that inactivty leads to more depression.... depression ... to more inactivty... inacivity to more depression... it's a vicious circle. If you sleep too much you are sliding down a depressive slope. You may have to do something you don't WANT to do. I know it's difficuilt. You have to go against all feelings and be more active just for the sake of it. The rewards may not be visible straight away. You can start fighting depression by realising/knowing that inactivity will make things WORSE. (The same goes for selfcare.)
To be clear: Inactivity /lack of self care (doing not much) does not mean mood stability. These things worsen mood.
If you and your hubby aren't seeing eye to eye it's natural for you to be a little upset. But it's not the end of the world.
Please look at the unhelpful thinking styles and other resouces on:
http://www.cci.health.wa.gov.au/resources/infopax.cfm?Info_ID=37
http://www.carmha.ca/publications/index.cfm?fuseaction=publications.showOnePublication&contentID=1
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Of course go to a doctor or psychologist to discuss your feelings.
http://www.cci.health.wa.gov.au