where a postpartum mom had a break down and killed her children or something
I'm here to tell you that pregnancy hormones are absolutely no joke. My mom had post-partum psychosis for six years (yup, it can last that long) and I was nearly one of those children who ended up dead as a result.
She would regularly put a pillow over my face every single time I cried until I was six and only stopped when I stopped crying. I have RAD because she would lock me in a room for hours on end and completely neglect any type of personal care that an infant needs.
I don't mean to freak anyone out or make it about me but "it's just hormones"? Is absolutely an extremely serious thing that can affect you and your child and your spouse for years to come.
If you're having these major depressive spells that are abnormal I'd highly suggest speaking to a doctor to make sure it doesn't turn into something that has long-term impact on your family.