OP I feel for you massively, this was me a few months ago.
2 under 5, I do all drop offs and pick ups, DH often works away, and I have an extremely demanding job. It's fucking shit, and I do think others who share the mornings, drop offs and bedtimes just don't get it at all. Those are the HARDEST and most stressful parts of the day hands down, and then you also get to deal with the tired and cranky kids in the evenings after your stressful day.
I get it. It's HARD. I basically had a mental breakdown.
Please get signed off with stress and take a couple of weeks to sort your head out, mentally recover a little and be less exhausted. Then take practical steps.
I changed my hours so that I had 2 periods in the week where I was not at work but had childcare. So I start an hour later one day, and finish earlier another day but I still send to after school club.
This means I have headspace and down time, even if it's just a tiny bit. DH won't understand because he has easy mornings and evenings and has only downtime. He needs to pick up all the other shit when he misses the mornings and bed time like cooking dinner, washing, chores etc.
I also insisted on a cleaner and she also does washing for me sometimes. Makes a huge difference.
Stop giving as much of a shit about work - you can only do what you can decide, you're replaceable to them, do the minimum for a while and don't put pressure on yourself.
Do the same at home.
Accept that until they're a bit older you will probably feel like you're spread too thinly, can't be the mum you want to be or the worker you want to be. Accept you are giving 100% and this has to be enough, no matter how much that falls short of expectations. You can only do what you can do!
I really sympathise. I only have one other friend who is a working professional who understands. We don't get much outside help either and the lack of time to yourself makes life feel awful.
Don't give up your job, have a cry if you need to, and maybe look at an extra half days nursery to give you a break xx