good day ladies

i need help. hubby works for an insurance company and for the past 3yrs they have been given assignments to do on the products the company offers, they also have to attend training and write tests (this is done yearly),while they still have to do their work. this is putting a lot of pressure on him and he cant cope anymore.
since all this started ive been helping doing his assignements,sleeping in the wee hours of the morning,even when i had a newborn,
this time around i feel that i cant do it, the thought of doing it (research and reading notes) depresses me, i also work and have kids to come home to and still have to nurse at night.
am i being selfish? i know he needs my help but Lord i cant, i dont have the energy to do it anymore, as a result im busy looking around for new work for him so that he can get out of the industry as hes'' not enjoying it anymore, so am i if he comes home stressed, tired and still having to do his assignments.
why do i feel so bad for not comign through for him?