I turned in my roommate who threatened to shoot up her workplace
How did it make you feel to turn in your roommate knowing what she was going to do?
I felt proud that I had the courage to turn in the shooter because she should be responsible for her actions and I don't want to pay for all the damages
Turning someone in who is violent is the right thing to do. You should focus on doing the right thing instead of having to pay for someone else's crime.
Yea but I'm worried that she might come back and hurt me since she got kicked out of her apartment now.
I can understand your fears and they are valid in this situation. It's okay to tell on someone who is trying to commit violent acts. If you are scared she might come back then you should discuss this with the police, although she will probably be in jail for a long time.