I agree, poetry can be very cathartic. I saw a documentary that explained that when stressful thoughts are spoken or written that it contributes to the brain finding solutions or simply feeling better. This has got something to do with when the electrical impulses are triggered in the language centres of the brain (and especially when the person feels heard) it can result in a soothing chemical (I think seratonin) being released. If you pent up your thoughts in the worrying centres of the brain this chemical is not released.

I'd like to be an art therapist one day because creating visual art has a similar effect.