Just let go if you are just degraded by it. It’s not selfish, I think. How could you respect other people if you alone cannot respect yourself? It’s not that you should mind yourself first before others ALWAYS, but it won’t make sense if you’d stay if you know there’s pain in the end. If that thing/person you are holding is really worth the world, then sure. Take the risk. But you’ve been warned.
Under the category of ‘love life’, you are called a “martyr” if you don’t let go after he/she had hurt you in various, unique and creative ways. I’ve been stupid once, and the only reason why I did hold on was because of the MEMORIES. Though later on, I realized how I’ve grown to be so stupid–it was not love anymore. I let go, and tried to search myself in other fields. And I could say I am happy.
Under the category of ‘work life’. The practical rule is to resign if your mind and heart do not say yes to it; when you can no longer dedicate yourself to your job. But before resigning, make sure you did not leave any work assigned to you undone. That’s what we call professionalism. If you “can’t see yourself” there and your relationship to your co-workers is comparable to trash, then finish your work, be professional and leave peacefully. Afterwards, find yourself in another place.
No one could actually tell you what to do. It would always be YOU who would make the last decision; who would let go if you don’t feel like it anymore; who would hold on if there’s a reason to stay. If there’s none, then just leave it there. Know when to seek help, know when to quit, and know when to hold on.