This is a massive adjustment, OP. My husband walked out on me and also I have lost both my parents. Good and bad days happen for no apparent reason. Loss, whether through death or divorce, takes a LONG time to come to terms with. I don't think the adjustment after divorce was any less difficult than after death. There really are no words for the scale of the adjustment required after a marital split. I'm convinced that those who haven't been there can't understand. You have to re-think the entire rest of your life, and come to terms with the fact that all your years henceforth, forever, will look different from how you had pictured them for so long. It's the ultimate rug-yank, and it will take a long time to truly heal. So be patient and kind to yourself.
You don't have to be involved with him for the rest of your life. Plenty of divorced parents rarely see or speak to the other parent. Once they're out of education, you'll only need to see him at very occasional family events, like graduations and weddings. In the meantime, there are parenting apps which mean you can co-ordinate without having to speak to each other. I think there's one called My Family Wizard.
When you are faced with a huge loss that you didn't want and can't control, there really is no true fix but time. It's a cliche because it's true. When you can't fix it, like you can fix a bad job situation or dating relationship by leaving, the best method is distraction. That's what I found. Set aside some time to be distracted for a time. For me, funny films or TV series and beauty tutorials on YouTube were it. Your mileage may vary. But distraction is the key. It's not good ruminating too much and trying to think of ways to fix the situation, when there is no fix. I wasted so much time that way, when I'd have been better of practicing radical acceptance.
I have been where you are, and I wouldn't wish it on my worst enemy. Sending you hugs and relaxing, healing dust. 💐 Better days are ahead, I promise.