What is the last situation where you became a toxic player?

We all have run into toxic players, someone who just won't shut up about their greatness or about how everyone else is trash, or repeatedly belittles others for mistakes. Most of us like to think that we aren't this kind of player, but we all have our moments. Be it bad teammates, a long string of losses, or some other factor that just leads to animosity, we all eventually show cracks, and those cracks create learning experiences.

I want to hear about times and situations where you became toxic due to a situation, and what you have since learned either from that situation directly, or since then that the situation is far less likely to occur again. This is about growth and learning, so please, if your lesson is as toxic as the situation, you might want to skip this. We aren't here for that.

I'll start. I played a game today, just ARAM, where someone wanted to trade their Sion for my Ashe. I did so, and proceeded to play the character as well as I could. Throughout the game, my team seemed to dive in and die while I was nowhere to be found, typically due to deaths from tanking, leading to a lot of situations where they had no tank and I had no damage dealers. I became frustrated and told them they needed to stop rushing into 1v5s and dying, which just lead to the game spiraling out of control. We had a very clear win, but we couldn't get all of our team members to be alive at the same time, which took a very clear victory (we crushed one of their Nexus towers before they even took down our first lane tower, I believe), and turned it into an enemy victory. We threw the game hard, and after days of only getting to play once or twice in a day, and losing every game, I was furious that we had lost with victory so easily within grasp. I ended up with an S- on Sion, no one else in the game had a similar rating, and most of my team was deeply negative. I told them all to take a break from the game for a while until they learned how to play in the post game screen.

After all of this I had to rush off to work and I started to realize that I never once tried to get us back on track. I just complained, once, and then proceeded to not really do anything to help them play better. No advice, no communication, nothing. We were high on the horse, and we needed someone to rein us in and keep us working as a team, but no one stepped up, and more importantly, I didn't step up. I saw a problem, did nothing to fix it, and then complained when it all went south. Even a game that was a very clear victory can be completely lost without communication and someone stepping up to help guide the team to victory.