From Experiance if you are suffering with depression it is far deeper than just feeling off it for a few days, Go and see your doctor, tell him/her how you feel and tell them you need a bit of time to gather your thoughts due to pressures of this and that ,
Stress at home and at work is serious and is hard to shake off without help if it becomes out of hand , Just keep your employers fully informed , tell them the basics and no more, Just send in the doctors note and keep them informed and get better in your own time ...