I'm 3yrs in to being a single parent, and I promise it does get easier. You work out what helps & develop a routine (my DC were a fair bit older, mind you). Silly things like downloading stories from CBeebies on the iplayer app helped at bedtimes on evenings when I was just absolutely frazzled.
In a lot of ways, I've found it easier being on my own, because I'm not carrying the weight of a difficult relationship, nor do I expect anyone to help me out - I know this is on me, so there's no resentment that 'FFS, could you not at LEAST have done this???'
You'll have bad days, we all do. I won't lie, the Christmas they spent with their dad, I closed the door behind them as they left, fell to the floor and HOWLED like an animal. I couldn't control the noises that came out of me. It was awful. But I survived it. So will you.
Two things that might sound silly, but have really helped me, especially in the evenings - firstly, podcasts. It's oddly reassuring to have another adult voice murmuring away in the background, even if you're not really listening to them. Secondly, online surveys. Seriously. You get paid for doing them (usually in cash or amazon vouchers), it takes up your time, and it pays for my DC's Christmas & birthday presents every year. It takes up your time, without needing any emotional energy.
to all of us doing this. It is hard in some ways, easier in others, it's not what we would have planned, but here we are, doing it. Online friends have been my absolute salvation.