Life is so SO hard when DC are small. On top of that, you both have very stressful jobs.
I think you need to give each other a chance. (Because I think no one should divorce or separate due to how you feel and behave when DC are between the ages of 0-5. That's just a grey mist of exhaustion.)
DH and I came close to splitting up when DC were that age. But instead we just made a few important changes.
Try and catch him for a chat one night, with a bottle of wine or beer or a cup of tea - something you both enjoy. Remind him and yourself how much you loved each other and what fun you had together, and how tough this year has been. (Don't blame him or yourself, just say it was tough.) Tell him you think you both deserve more fun and kindness in your lives and that you want to make an effort for this to happen.
The changes that helped us were:
Split the weekend (or days off if you work shifts) into four chunks of four hours each day. (Assume 8 hours for sleeping - even if you get none.) If you get two days off a week, that should be 8 chunks of four hours.
Agree to spend one chunk of four hours both doing stuff that makes home life run smoothly: shopping, cleaning, laundry, house maintenance etc. Both do this at the same time - each be in charge of one child while doing whatever you are doing so no one feels resentful that they are expected to clean and child mind simultaneously.
Agree to each have a four hour chunk of time to do whatever the hell you want while the other one has the kids. You can lie in, go to the shops, meet a friend, do a fitness class, have a long bath, whatever you want. You plan in advance when those hours will be. The other person takes the DC out or actively occupies them during those four hours if you stay home, so they can't pester. This took some practise. I found when DH took DC out I was running around making them all packed lunches and sorting the nappy bag etc. I had to learn to stop and make him do that for himself, since he never did that for me. I also had to ask him all the time not to let DC run in and jump on me if I'd chosen to lie in in my chunk of time. He had to actually keep the DC busy.
But that changed our lives. We never felt resentful of each other because we had equal amounts of time to ourselves and it was guilt free. It was long enough to go out for the evening to a film or dinner with friends.
Then another two chunks of four hours are for doing stuff together as a family. Put them together for a full day out or have two half days where you do stuff at home or outside. But make it fun. Harder during lockdown, but having fun together as a family was a massive shift in our relationship that really strengthened it.
One chunk of four hours is for you as a couple. Get a sitter, even if you just go for a walk in the park and for a quiet drink. We tried to avoid going out for dinner because you just sit exhausted staring at each other with nothing to say. Better to do stuff that is fun together. Hard during lockdown. We used to go to gigs and comedy clubs but they are all closed right now. You could try doing something sporty - kayaking or wild swimming or cycling together.
And the other chunks of time are just for getting through 'stuff'. Like feeding the kids, bathing them, sorting email etc. The usual things that take up time. But these are so much less of a slog when you know that every week you get half a day to yourself, half a day with you DP, and a whole day or two half days doing something fun together.
It might sound really over-planned but it was so helpful to us.
The other thing that helped us was just to make ordinary life more fun. Put on music you both love when you are cooking or cleaning. Watch comedies together. Share funny stories from work with each other. Give him some compliments or remind him of a good time you had together. Share cute/funny stuff the DC do and say. Focus on the good stuff, even if there's not much of it. The more you do, the more of it you notice.
Sorry for the essay but you did ask for advice!