OP, I have been reading your thread and haven't commented as you've been given so much brilliant advice and support but I wanted to share a quote with you that really helped me when I was in a very similar situation.
It's from a Caitlin Moran talk in 2016 (which is when my XH left) and I still sometimes refer to it even now on difficult days.
In the weeks after my ex left I used to literally pace the house a minute at a time. The minutes became hours and then days etc etc. But if getting through the day feels insurmountable, just get through the next minute.
You will survive this, you will come out the other side.
"You will never, in your life, ever have to deal with anything more than the next minute.... The minutes always come one at a time, inside hours that come one at a time, inside days that come one at a time....You will never, ever have to deal with more than the next 60 seconds.
Do the calm, right thing that needs to be done in that minute. The work, or the breathing, or the smile. You can do that, for just one minute. And if you can do a minute, you can do the next."