Understand that the whole disfellowshipping thing is designed that way to make you feel the way you are. It's not normal, its not loving or nice and they GB know it. It's a control mechanism that's underwent modifications since it's first inception in the 1950s.
My advice would be to go along with the charade for now. Sure, sit in the main hall on your tablet. Pretend to follow along. Maybe even get reinstated if it comes up to make things easier for you then get a job and move. While you're going through this make sure you make non witness friends. Remember, this only works because they expect you to have no one else. That's why people go back. If shunning didn't exist nobody would return.
The guilt you're feeling is absolutely normal. You're going through a situation that most people in the real world are never faced with and totally unprepared for. Remember though, that YOU'RE the one that's normal. You're smart, you've figured this out young.