It can be labeled as “the world is out to get me”, which manifests as continual anger.
It can manifest depressively, since all normal actions are harder for the person who is chronically anxious.
In order to detect any chronic emotion, there have to be cycles in it. To feel anxiety clearly, there have to be times when you don’t feel anxious, when it fades. Then you can say “X makes me anxious”, because it stands in contrast to Y.
But if there is no Y, perceiving things clearly is next to impossible. The healing process consists in creating Y from scratch, without experience in how to do it. It is extremely possible, but it will inherently feel strange.
To become more sane, you must realize what part of complete sanity you had been lacking. This feels like a loss, or a disorientation, perhaps even a dizziness.
Perhaps if Sartre has pushed on, he would have found the other side of his nausea, and he would have found that the Others were him, and that he created his own hell.