keep wishing I wasn't a mum anymore
This is so telling. You're so low on resources you can barely function, so of course you feel incapable of being a mum right now. And wishing you weren't anymore, is simply your brain's way of saying "I can't do it, it's too much".
I'm not a mum, but I have been in this same, very dark place. I promise, it does get better. The more support you can have from your doctor, mh team, family and friends the better because you need to focus on taking care of yourself right now.
Just take things one hour at a time. What do you need between now and 2pm? To curl up and sleep? To eat or cry? Maybe go for a walk?
One hour at a time got me through the period you're in. Sometimes it's just staring at the TV, other times it's doing something that needs doing.
Don't expect too much of yourself right now, the bare minimum is absolutely fine.
Keep your blood sugars level. Eat something proper every day and try to eat regularly, even if you just graze. Keep drinking water and avoid anything that precipitates a drop in mood.
Keep putting one foot in front of the other, even if you do need to stop for a break, because in less time than you think you'll be planning in terms of 1 day ahead instead of 1 hour. Then 1 week, then a month.
You're doing fine, op and we're here for you.