I think your DH does not understand how mentally, physically and emotionally draining being at home with 2 young children actually is.
And maybe you don't understand how hard he works and the pressure that is on him.
It's not about who has it harder. But I think your DH needs to understand that being a SAHM is not a 9-5 job, it's relentless. Whereas he may have a hard day, at least it finishes at a certain time.
Your day doesn't have an end time does it? You can have the day from hell, with screaming, tantrums, mess and you can't think "oh well at least it's nearly finishing time"
If I were in your situation I would either a, bring bedtime forward. However, it seems bedtime suits you so then in that case I would agree with your DH that for 2 evenings a week he takes the DCs out for an hour. Doesn't have to be the supermarket, maybe a walk or a drive or visit friends/relatives. Then 2 evenings a week you could do the same. Go shopping, go for a walk, go to the gym.
And the final weekday evening you spend together. Do the bath/bed together etc.
Would that work?
Oh and just to add, please don't question yourself as a mother. I work full time simply because I could not be a SAHM to 3 DCs. I just couldn't do it.
I love my children with every single part of me and now they are teenagers it's less relentless monotony (but more drama) but I would have been a terrible SAHM.
Yes, it's been hard working full time and getting everything done, especially when they were small but the commute to and from work, with headphones and a book was blissfull. A full 27 minutes twice a day to just...sit.
And your DH gets this time. And you deserve it too.