<human>: So my friends and I were 2v2ing in LoL. My team was losing pretty badly, and then they wanted to just end the game for various reasons. My team declined because we wanted to catch up and make things more fair for a real 2v2. It eventually escalated to a point where I was arguing with a mate on the other team about how burst dps is overall superior to sustained. For more context:

 I didn't approach it maliciously at all - but one of my counter arguments has clearly hurt my mate enough for him to leave all the clubs we joined together. Basically, his argument was that his abilities were all skillshots (so takes proper aim to use) and that mine were all click and point (so just click and it happens, no aiming needed). I said that this didn't matter regardless because he was better than us anyway (he's a bronze 5, we're not even ranked) and skillshots probably aren't even a hindrance to him. Maybe I'm just a blunt person and not as sensitive, I don't know, but like I said, this appears to have hurt him enough to just quit the game and leave our clubs. 

Regardless of right or wrong here I feel like a massive asshole (it's never my intention to hurt anyone's feelings. I suppose it's in the nature of an argument though). He hasn't blocked me so I'm hoping I can clear it up, but I'm not sure how. Do I just go "Hey, I'm really sorry for being an absolute asshole. No excuses. Sore loser syndrome got the best of me." (wait that's an excuse isn't it?) What else can I say?

Can you summarize the given text in a few sentences?
<bot>: pissed off a mate by saying something that hurt his feelings, and he just quit/left. How do I say I'm sorry for this?