PhD student where TA work leaves little time for PhD. Is it even worth it to finish this PhD?
Everyone in academic CS gets below market pay. It sounds like they made you a department IT guy, and I've never heard of that, but it may not be too unusual. 

You might be burned out, they overwork you. You can:

1) talk to your advisor about all this. Maybe they can lighten the load. TAing and being an assistant sounds like too much. 

2) take some time off. Go into industry for a year. It sounds like you want to do that anyway. Departments have a process for being on-leave. Make some money, get a hobby, don't think about your research for at least three months. Then decide if you want to go back and finish your PhD.