This does sound like a standard depressive episode. With cause, break ups, parenting stress, and a lack of self care time all contribute. If depression isn't something you normally cope with, and it isn't unusual for someone to have a depressive episode or imbalance workout having a mood disorder, there are usually a lot of therapy resources to get through smaller more isolates episodes. I would look to see if there are any in your area. If you do think it might be a bigger issue, I would consult with your PCP about it. You've got this though. It sucks now, but it won't always feel like this.
I think at this stage of life, it’s likely just “normal” depression and not postpartum which would be triggered or influenced by hormones. Depression is incredibly hard to deal with. It’s good you’re eating! I would recommend looking into therapy, if possible. I’ve had anxiety and depression forever and having the right resources really makes a difference.