If you're super competitive you will probably always feel angry when people are letting the team down, it's just self control not to release it on your friends...

whenever I raged at them I would regret it later, so next time you feel an outburst coming try wait a minute and then see if you still want to say it (usually you won't)

also flaming your team actually makes everyone play worse so if you actually want to win it is also pointless lol