Why is it so torturous? For me, I'm a software engineer, and I became one because I'm obsessive. I like to think about a thing all day every day. The most I get now is maybe three 90 minute chunks a day, maybe a couple three hour chunks a week. If you're not like this you won't understand how it feels, but if you are, you'll know what I mean when I say learning to live without this kind of thing (I guess the term is need for cognition?) has made me into a completely different person.

It does get better though! We do daycare so when they're old enough I get a regular work schedule back. Definitely no nights or weekends though; those days are gone for the foreseeable future. But, like you, I'd do anything for them and I don't regret it. It's just hard to overstate how huge the change is--you legitimately are forced to become a different person (or, I guess, you can choose to not be a very good parent, idk)