Don’t you have a lease? Did your roommate sign it? If so, they can’t just move out in the middle of it & stick you with the rent. Legally, whether or not they are living there, they are financially responsible for half the rent for the term of the lease unless an agreement can be reached that is agreeable to all parties. Maybe you could make them find you a replacement roomie.
Excuse the highjack but, Damn horseflesh. Reading this really brought tears to my eyes. I’ve been through it. Try to not blame yourself. I had a lot of long nights sitting up trying to figure out why I couldn’t make her happy. It helped when we learned to communicate well enough that she could help me see it wasn’t my fault and I could help her see I do not judge her or think her weak.
I hope tomorrow brings a better day for you.
The medical literature suggests that post-partum depression can be one of the more difficult types of chronic depression to treat. I have no experience with this specific type, but I have been in your general situation. All I can tell you is that it got better. Keep hoping, take care of your kids and yourself, and best wishes.