- You're doing this to yourself, buddy. There's always more work to be done; it's not your responsibility to do all of it.
- You're not going to outrun a train by running faster on the same railroad tracks.
- When (not if, but when) you finally crack up, you won't get a word of thanks for your efforts. They'll just ease you out of the company (gently or, more likely, not) and hire someone else to replace you.
My advice is:
- Gradually start padding your estimates until your work fits into a 40 hour week.
- Learn to say "no" or at least "not right now" to requests from other people and other teams.
- If you get dinged by your management chain for reducing your pace, find a new employer ASAP. Good managers want their employees to work at a sustainable pace because replacing good employees is expensive and risky. You clearly don't have good managers.