I am not good at expressing my emotions. 
I keep my thoughts and feelings piling up, for myself. but even then, sometimes emotions need to be let out, one way or another.
‘negative’ emotions like anger and sadness get expressed in dark thoughts. I make those up on the spot and it then plays like a movie until I snap out of it. when I might be feeling sad or angry, I get a very (shocking) dark thought for a few minutes. a few tears might drop. then I snap out of it and go back to what I was doing. like nothing just happened. 
those dark thoughts are all different and sometimes hard to remember (they tend to fade away quickly after) but they always involve me getting very hurt both physically and emotionally. it’s a bit embarrassing for me to say. I guess that is a way I relieve some of that sadness or anger.