Hierarchy of needs. You need to look after the DC in the sense they eat, sleep, are clothed, washed do their basic schoolwork. You need money coming in to cover house, food, clothes. You need to eat, sleep etc.
Beyond the essentials consider all the periferals.
Are you running ragged going from activity to activity with the DC?
Are you making constructive use of your mum if she is able to help to counter the negative impact of the criticism? My mum drove me up the wall so in the end in the full knowledge she was going to judge and make her feelings of my inadequacy known I used to leave the ironing and save stained clothes to ask her advice on. Even though she huffed and puffed about how I was getting behind with an ironing pile that big, it focused her critique in that more manageable area and it helped me out.
Do you have energy for a boyfriend who is turning his back on you struggling - if he's hanging around and not helping out would you be better off backing off to just dating when it suits you?
Are you eating well and getting to bed early enough to have a good night's sleep, Everything feels worse when you're tired?
Housework if it's getting on top of you maybe as a minimum go for one tidy room that you can retreat too. I found keeping some of the DC's stuff boxed out of reach helped stop too much toy spread around the house.