I spent a few years in the angry state. It coincided with the first time I came to the forum, actually. lol But, for me, it was actually more that I chose to be angry because I didn't want to feel the sadness and depression that was overwhelming me. I couldn't take it anymore and I didn't want to feel the devastingly raw emotions that were trying to flood in. So yeah, I just let myself be angry because it overrode the other emotions.
Though, I can say the longer I stayed in that state, the worse I got. It was like instead of choosing to be angry, the anger was controlling me. Eventually, it got to the point where I would get so angry and worked up, I'd have anxiety attacks and start to hyperventilate. And of course, that just made me even angrier, so I started punching things. (NOT living creatures) Mostly walls. After having to patch a few holes, I started in on the solid oak and steel doors. More damage to me, but I didn't care. The pain would release the anger. It was not healthy, please don't do that.
Eventually, I started to realize it wasn't healthy and it wasn't helping and I asked myself why I wanted to be angry and why I was turning into that person. But, that also meant having to confront the other emotions that I was terrified of. I started meditating and that helped a lot with the anger. A punching bag is an excellent idea. It allows you to get your frustrations out, without hurting yourself. Any type of exercise helps. Taking yourself out of whatever situation makes you sad/angry/whatever will help, like, go for a walk instead of sitting at home alone or something. Get yourself out there, do something, stay occupied, help others. Keep looking and trying things until you find something that takes those emotions away, whether it's the sadness or the anger.