Over the past few months I've taken on a lot of roles that I never asked for nor signed up for. I was hired as a developer. My boss took on a project in which I didn't have a say in the timeline. Due to severe over estimation of how quickly 1 person could build the project he needed to bring on 3 other developers.
Now, to say that these developers were green would be an understatement. None of them had experience writing code at production level. In order to keep this system from blowing up I was often spending much of my time reading their code to make sure it wouldn't do just that, going over reviews, or sitting with them for and hour or 2 a day helping them figure something out. In many cases an entire day would go by and at about 3pm I'd get a message that they couldn't figure out a bug and needed me to do something for them or they'd have to take another day to figure it out.
My boss has been very busy with another client so he's been asking me to meet with and email back and forth with the client for my project on a daily basis. He has also wanted me to look into database management, a field of which I've never even claimed to have a large amount of knowledge in.
Up to this point I've been working 12-16 hour days for the past 2 months and I don't see this ending until September. Even when it does I don't think that it was okay that he put all this on me to begin with, but I acknowledge that I probably shouldn't have let him.
I've decided that I'm not going to work 12-16 hours/day anymore while only being paid for 8. He's asking me to do the jobs of several people, hasn't offered me any raise or compensation, and has been very insistent that I still produce just as much code as I did prior. I'm going home at 5pm and what doesn't get done will need to wait until tomorrow.
When/If he gets upset that work starts stalling how do I politely and professionally let him know that he's asking for way to much from 1 person?