So to keep up with technology is that I sometimes switch from customer (if you have the chance), then you will automically learn new things. Whether they are old or new technologies.
Another thing is try to follow sometimes courses, seminars (hard- and soft skill), during working hours preferably. Then it won't affect your private time.
And if I have time when my 3 kids are in bed, and I still feel the energy to create something. Force myself to keep my side project small, and don't be too hard on yourself when you don't finish it. Because you definitely learned something.
Since it is your first job: Try to learn as much as you can. Gain experience and then leave or see if you can get a different assignment.
Is your boss really an asshole? Or does he want to achieve something where he needs you and your skills?
See if you can work one day less per week and spend that day on your hobby, or code something without stress or pressure.
my 2 cents...good luck