Understaffed and extremely overworked to the point of exhaustion and burnout

I work as a SDE-3 (7years yeo) at one of the largest b&fs companies in the world. An year ago, our team was this one big family with a good wlb and pay with everyone stepping in for everyone else which is very rare in today's world.

Recently there was a change in the management structure and the team was split into 2 different teams with 2 different managers who have different style of working. One is a happy go lucky, no tantrums manager who is just bothered with getting things done only during office hours and is even okay if things move at a slow pace while the other is a complete workaholic (who is always logged in even during weekends) and a hard task master. Unfortunately I was placed with the latter.

Initially it felt good that my manager is a workaholic and contributes to the project as we are executing a very complex project of converting legacy banking code but now it has started to feel burdening to the point of being mentally and physically exhausted all the time.

A team of 4 people is doing the job of 10-11 people and instead of hiring experienced folks, they have hired college freshers. This meant that along side development, documentation and scrum meetings we also had to do KT and teach them pretty standard SDE stuff. Our job starts at 10 AM and ends at 2 AM the next morning almost everyday. Inspite of such work hours, the sprints are getting backlogged to the point that even if we work 7 days a week for the next month or so, we still won't be able to execute all of them. And on top of that the manager just keeps on loading work after work. Over promising the upper management on getting things done.

I got married recently and did not even have the luxury of getting marriage leaves (except on the 2 days of marriage) and took a short 3 day honeymoon break after a month inspite of having 60 days of pending paid leaves. My wife has also started questioning if I have married her or my employer.

I have gained a lot of weight and dark circles and looklike I'm in my late 30s rather than 31. Can't even think of leaving this job at this point without securing another one. But with the 16 hour work days, I don't even have the motivation of studying anything tech related on weekends.

All my 3 other colleagues are also in the same boat!

End of rant!!