I'm not a formal guitar player, but i have played drums for 12 years and have played in 4 bands. I also listen to Opeth obsessively and understand other black metal patterns.(thats just background filler crap). I have learned there aren't any shortcuts in playing music. You just have to practice ALOT and care enough to make it a priority. Sorry about your depression. Just pick up the guitar and start playing. Make up for lost time. I tried out to scream in a metal band. They wanted me to continue but i had too much school so i didn't. Just use ur stomach and from the deep chest. It will be hard at first but you have to use your diaphragm like when singing and add a little throat in there. Dont use all throat because it will tear out your vocal chords, especially trying to raise your voice over the sound.
Hope it helped
