In trying to recover from whatever crap it is you are feeling yet again when you know even if things get better at some point it is only ever temporary. The issues don't go away, the underlying cause doesn't go away. The only difference is that you can better hide from the world just how crap you really feel.
Why bother with exhausting yourself trying to feel better knowing you can't maintain it. Or bother with attempting to start to get on top of things when you know it will all fall down in a heap again. Knowing that if you get better enough for your child to come home that you will only put him through it all again at some point.
There really is no point to trying to get over the don't cares