I hear you. It’s been incredibly difficult for you lately and it is relentless. I’m a single mum too, but my DC are 7 and 8.
I can only tell you what seems to be working for me. I stopped keeping it to myself and started telling people how I felt. In my case it was a trusted colleague (we are still wfh) then my GP and a local helpline. I did not want to face up to it but getting it out in the open has helped. I can’t emphasise the importance of talking to someone enough.
I planned out a very rough, achievable daily routine that includes a few minutes of self care, which previously just didn’t exist. I find the Headspace app helpful, but Smiling Mind and Happify were recommended to me too (not had time to look at those ones yet).
I do practical things like prep as many meals as I can on a Sunday so I have less to contend with during the week.
I get up earlier so I can have some peace and gather my thoughts before the day starts.
I’m in Scotland so my DC are back at school and what a difference an enforced routine has had on all 3 of us already.
Try to get outside every day, even if it’s a walk round the block. It might not seem worth the hassle of getting the one year old and buggy down the stairs, but view it as an essential.
However, these are just practical things that help me stay afloat. Citalopram has helped me more than I can say, as has talking. I found talking to a local helpline easier as I felt more anonymous, and I really do think you should speak with your gp as you may well be depressed, anxious, stressed or all three.
I’d be happy for you to PM me in confidence if you like. Please don’t suffer in silence. Even posting here is a step forward.