Groups . Postpartum depressive disorder is real, is not just due to pregnancy, and requires aggressive thorough help. Medications, counseling and most importantly support groups of women who have successfully dealt with this are the best treatment options. Men and husbands need to be educated about this condition as they are often dismissive of it, thinking it's some some variant of women "things.".
Find a mental health. Professional who treats depression. Ask the professional who diagnosed you for help or a referral, or start with your ob/gyn or pediatrician. What you are experiencing is fairly common. Post-natal depression can be from rapid hormone changes, stress & sleep deprivation of having a new baby, lack of emotional/social support, etc. Talking to other new parents can be helpful. Don't suffer alone.