In this sentence "bent out of shape" seems to mean drunk. The phrase "bent out of shape" also means to get angry. Example: "I failed my math test yesterday. I'm still bent out of shape about it!" In the sentence "you had to find a poison to……image was terrifying." the word "poison" means a type of alcohol. In America, some bartenders will say "pick your poison." which is a way of asking "what alcoholic drink do you want?" So it seems like what the author is saying is someone had to get drunk before being able to function. I hope that helped!

In the context given I think there is more to it than Alan's or Amani's answers. By bent out of shape, the writer is referring to the stereotype for jazz artists who always seem to have had a troubled past or bad experience that has had an effect on them and therefore their music. These experiences make them slightly different to most people ie bent out of the NORMAL shape. The reference to poison is saying that to become part of the jazz world, you have to experience your own particular suffering before you can look inside yourself and see what you really are and then use that knowledge to form your music.

"bent out of shape" - This could mean "insulted", "angry", or "intoxicated by alcohol or drugs". In this case, its probably the last one. "You had to find a poison to let you look in the mirror." - This could either refer to the "alcohol or drugs" from above, or it could simply mean that you have to go through something traumatic before you really take a look at yourself. "the reflected image was terrifying." - This means that Baker's image is terrifying to either himself, to the speaker, or to both of them.