When it comes to getting along with people, it's not really something that you learn to do. There are some tf2 players I would never team or hang out with and thats fine but your issue seems to be that you can't stand to be around anyone you come in contact with which seems to be a different thing than what I've experienced.Maybe you could elaborate on what things specifically that annoy/frustrate you with other people?
As for getting frustrated in Jump maps/MGE/DM that's just something that comes with how you choose to approach the game. I used to do Jump maps/MGE/DM because I wanted to win in them which made me get frustrated and raging at the same things that you're describing. It wasn't until I started going into these things with the mindset of getting better that the rage sort of disappeared. In one of my earlier seasons my practice would only come from scrims and matches and that worked for me for a while, because I had a tendency to burn out from grinding DM all day long.
If you feel like you don't find any enjoyment with the game anymore, take a break. It may take a day, week or a month before you feel that urge to play again, or not at all, which is fine. If you don't find enjoyment with the game anymore, the best thing you can do is to just stop playing. Playing something that makes you feel bad is never going to end well.
EDIT: A thing that I use to do in DM is to not look at the scoreboard when I play, sometimes the will to be on the top of the scoreboard can tilt you.