Refuse to be depressed, just want to be a good wife and good mother

Refuse to be depressed, just want to be a good wife and good mother.
Like the title, has been trying to play these two new roles, but often feel powerless, helpless.
On the one hand is the joy of the arrival of a new life, on the other hand is the endless effort to stay up all night, hiding behind is that I can not emotional self-control, while forced to smile, while crying at night. Once upon a time, I felt that depression was far away from me. Now, I am struggling in the black hole of depression.
The reason why I thought I might be suffering from postpartum depression began one day when I inadvertently read an article from a public trumpet about a second-born mother who wanted to kill her child and then commit suicide. The topic was frightening, but the content was real. Although this extreme behavior is not recognized, I am amazed to understand this mother's inner feelings. I was scared by my own subconscious, I found some postpartum depression test questions on the Internet, the results showed moderate depression, suggest to find a psychologist...
I once questioned the reliability of this test because I never believed my depression was so serious. Perhaps this time is too much annoyances, mixed up, depressed, but failed to timely vent.
Complaining, but there is nothing to say in reality, I find that I am already a person who is not allowed to complain, because in my family, relatives and friends, I am a very happy person. What do you think?