To see the dark side in everything, yes it is exactly how it works. I know exactly what you mean, even if maybe my crisis are less severe, particularly since I take antidepressants (which means 5 years). Well, I am even more simpathtic to you than ususal, because of this common theme, and becasue we are the same age. According to Dante, 35 was the middle of life's walk (il mezzo del cammin di nostra vita) and it is easy to think that most of life has been spent, so miserably...
Well, cognitive/behavioral is the therapy I am doing since 5 years too. My T never meant it as "practicing skills", as I often read in books... but he is helping me to stop telling lies to myself. My lifestyle IS changing, and I will see if that will stop the pain.

Well, if you feel that your work with cognitive/behavioral is over... do you think you may try the other approach, the psychodinamic one? Psychoanalisis is known to be painful and lenghty, but you already know pain and have plenty of time... Maybe there is an old rusted nail that really must be removed from the wound.

I don't know, just a hint to mean that you should not give up, but keep on trying.

Really, the best of luck