Out of control?

I'm feeling very overwhelmed today. I have a quiz in algebra (my most hated subject) tomorrow, lab homework and a four page paper due Wednesday, and a big biology exam on Friday. Needless to say my house is a disaster! No one has gone to the grocery store in weeks, and my household to do list is longer than I can remember. To top it off, the thought of holiday prep is hanging over my head. I really need to take a step back to breath, regroup, and plan. What do you do when things become overwhelming?