If there’s a clear line between you and your 3 colleagues that you won’t work more than 50 hours per week and they will, I’m not sure what you else you would expect. Were you not already paid for the first 40-45 hours per week you worked? I’m sure you do high quality work and make sacrifices for your job in certain ways, but quantity is its own kind of quality.

Also, how would you feel if you had one subordinate who was always asking why about the deadlines you set and challenging you? Even if that subordinate was sometimes right, that’s not going to endear him/her to you.