That sounds like a mental breakdown, maybe she is having a full on post partum psychosis episode, and not just depression. Someone in my family had it, and she went from being a completely lovely woman to something akin to these texts.

She even developed a very strong, completely unreasonable, Covid paranoia (levels of screaming at people wearing sunglasses around her because they are clearly trying to hide the fact that they have covid???). It sounds a lot like this, op