I’ve not got a lot of advice to offer, because what you’re going through is hard and sometimes there’s no easy answer.
I will however tell you from one stranger to another that the shame is misplaced. You have nothing to be ashamed about, because you’re doing the best you can. Sure, some hypothetical you has a shiny clean house and looks like they have all of their shit together but that’s not a real person, and that standard is not useful to hold yourself against. Your mil may very well have a spotless house but you can bet your arse she has other shortcomings where you are absolutely killing it.
Shame like this is almost always a learned reaction from some past events, and almost always it’s utterly unhelpful. You’re getting stuck in a shame spiral treating yourself like shit and then feeling so terrible that you’re in no position to dig yourself out. Try not to hold yourself to impossible standards. Treat yourself like a good friend - do what you can, and then give yourself a break. And try and recognise the areas where you’re doing pretty great, even though the house is a mess. Internet hugs.
Not really. I reckon most aussies would leave the spider be, and call it cunt only in an affectionate manner.