Late at night, this thought tends to arrive: it will be like this forever. I will never get a moment of quiet again. My life is over.
This is catastrophising, and it is the single most damaging cognitive pattern in tinnitus. It is also, in nearly every case, false. Most people with chronic tinnitus do habituate. They still hear it, sometimes; they just stop suffering from it.
A useful technique here is cognitive defusion, which means putting a small gap between you and the thought. Try this script in your head. "I am noticing that I am having the thought that it will be forever." Read it slowly. Notice how the thought moves from being your reality to being an event in your mind — one of many today.
You do not have to argue with the thought. You do not have to prove it wrong. You just have to stop standing inside it.