the key is to get plenty of sleep..sleep deprivation is one of the reasons for depression, when your baby sleeps, you need to get a power nap, forget about the housework, because housework is never ending, let the house go unkept for a while, concentrate on yourself.
also see if you can get some help, ask someone to look after baby for a few hours, go into a separate room so you cant see or hear the baby, you need your space.