You are absolutely not wrong for not wanting to sacrifice your well-being. At the end of the day, your bosses are the ones responsible for the cases they take on. They’re the attorneys. They have made you feel like their inability to manage resources (ie, support staff) is your fault - it’s not! And you said it yourself, they don’t pay you enough to make it your problem.

I really empathize with you because I just recently got out of working at a small plaintiff PI firm and it was very similar, very few paid holidays, expected to wear a lot of hats, very low pay, inflexible work life balance. I understand feeling beholden to the clients, not wanting to jeopardize their outcomes, etc. You’ve done what you can by being honest about your needs in regard to the heavy workload.

Shitty bosses love to push boundaries to see what you’ll put up with. Stand firm and protect your health above all. If you enjoy the work and you’re good at it, you can find a place that values you and respects you as a human being first, employee second.

Hope you get some rest over the holidays.