You've never rage quitted before? Everybody has bad moments. You had a bad moment just then yourself, when you called him a retard (that isn't mature, acceptable conduct). We just need to recognise that we can avoid these bad moments by thinking it through and calming down. (le) has been very good to us. No, I'm not going to cancel our alliance.
It's really interesting, and helpful, to read about Stoicism. It's all about knowing that you can control your destructive emotions - that you have authority over how you feel. It's really interesting stuff, and learning about it has helped me grow as person.