I think metal is the best way to channel some of the darkest feelings you experience. And without that channel, I could have easily drowned in them.
At its best, metal gives you the power to keep fighting when life kicks you in the teeth.
My all-time favorite has always been Sentenced, active bands I would like to mention are Korpiklaani and Poisonblack, but there are a million great bands and artists around here and more to discover.
I think the best way to relax is to go see a good band play live, and I prefer smaller clubs to big festivals ( this is because I quite dislike people in general, especially masses of people)