For me, lockdown has been brilliant for this.
Did it hurt when my ex married another woman? Yes.
Would just one minute of lockdown with him have been absolutely unbearable? Hell, yes.
Does it hurt anymore? No.
It's still unfair that his wife got the benefit of my hard work, but she also got the bits of him I couldn't fix, and the body that has aged so, so badly. What a prize. Me? I got to spend the last 6 months of my life without being judged and/or controlled by him, and having space all to myself.
There really is nothing like being quarantined to remind you how glorious it is to be single compared to being trapped in a bad relationship.
Go on - just imagine what lockdown would have been like with him in your home. Don't you feel better now, knowing that's not something you had to put up with?
He wouldn't have helped with your DC - he would have left you to it, with you growing more and resentful as you got more and more tired and he did less and less. You would have fought, and you wouldn't have been able to go out with friends and get some space, because of lockdown rules. Your DC would have picked up on the shouting and become a little nightmare, because all children, even the good ones, will act out when they hear their parents fighting.
Picture what the reality would have been like, not some rosy vision of happiness. You know exactly what it would have been like.
Now, aren't you glad it was just you and your DC?