I've been in a toxic environment for a long while. When I'm nice and don't need anything, things seem fine, but I'll get very odd evaluations filled with clearly biased interpretations and personal insults to justify rating me far below my productivity level. When I stand up for myself, it's draining but I usually get some support from upper management. This has been happening for 6 years and I'm tired. Quitting isn't an option. I'm happy with my work duties and everything else. Should I stay quiet, take the insults and try to stay happy and distant, or should I check out for my mental health?