For me, after I'd lost about 100 games, I got used to it... so it kinda surprises me you're as high rated as you are and you're upset.
I guess I still tend to get upset when I lose if other things in my life are bothering me. It's like I get mad at the chess game as a way of letting out that frustration.
But at least online, I usually never stay mad more than... 30 seconds or so.
OTB it's different because so much effort is put into the game. I might feel bad for days, but that's just part of being human I think. No need to fix it.
It happens to me that when I lose in chess I get depressed or angry, as you think you can handle these negative emotions, thank you very much in advance