OP: I feel your pain. Worked at SAS over 25 years. My final years there were in management. Was there during the great years and also experienced the downhill slide from greatness to merely goodness. Saw too many instances of workload imbalance. Outside of my team, I saw more work piled on worker bees while slackers were allowed and actually rewarded for coasting. Infuriating. In most cases HR was a hindrance instead of a helper. Same for management above me. That left me with limited options of what I could do(or be allowed to do) to make work life at SAS more enriching for my direct reports. Those options became fewer as time marched on. Realize that when/if you talk to your manager about your concerns. I suspect their hands are more tightly tied now than when I was there. A troubling and unsustainable trajectory...
Age allowed me to su-k it up for a few more years then retire. That may or may not apply to you.
Had I been younger, i would not have stayed to endure the painful experience of SAS' greatness spiraling downward to just "good". I would be left and worked independently for myself. Providing SAS services that customers still desperately wanted yet SAS was unwilling to continue providing. The money(back then) would have been almost 3X my salary. To repeat what I said earlier, this may or may not apply to you.
My advice for you is to stop giving them 50+ hours a week. Do 35 honest hours. Adopt a "meeting expectations" mindset rather than "exceeding expectations". Make up for the time that got stolen from you and your family. While that may never be an attainable goal, there is self gratification of exerting the effort.
Time is the most precious gift that you can ever give. So give it to those who value you instead of those who just use you. Good luck.