Absurd amount of toxicity from another turns on me?

Okay so I just had a match not even 5 minutes ago where I was playing Nidalee jungle, and I had a Nunu top, and we were against jax top/volibear jg/nami support. Well here's the rundown of what basically happened. 6 minutes into the match, the enemy volibear comes out of nowhere and kills me and then what happens? Nunu says "GG this nidalee is feeding volibear and is fking retarded." So I asked him how the hell 1 death was feeding, and he proceeds to say things like calling me retarded, saying im sh*t at the game because i started Q in jungle as nidalee, etc. etc, and later in the game he starts saying in all chat that i was shit and fed volibear (he had 2 kills off of me at this point i was 0/2/0) and so I explained how I wasnt feeding and said to the others that they just need to report nunu, he's being absurdly toxic and I havent even fed. And what happens next? The enemy Nami and Volibear say im just fking trash and they didnt see Nunu say a single thing in all chat. I went to screenshot what he said but I didnt get to because people were typing back and forth so I lost track of the words he started off with but did get some that he said about the enemy fiddlesticks mid, saying he was retarded and that i must be his brother. Anyways, at the end of all this we FF'd at 20, and I went ahead and reported Nunu, and well what happens next? My mid Ahri reported me (she said i was seriously bad and am being reported for int. feeding, I ended 0/3/1.) Nunu reported me for obvious reasons, and then volibear and nami said they were reporting me for "flaming" Nunu, (which I did not). Now this is where I am PROFOUNDLY ridiculed. I just got banned for 14 days, and I didnt receive a single notification prior to that about a toxic player being punished (which wouldve been Nunu). There is in absolutely no way, anything I said in that match was offensive or anything, and I'm just completely freaking baffled right now. I was expecting Nunu to get banned or restricted or anything, but thats more than unlikely, and here I am with a 14 day suspension. This has more than settled the ideal of me wanting to play league anymore. I really cant take this type of banning system, it is very improper and I really dont see any way its helping the community. I'm just really at a loss for words right now and will be trying to appeal this ban and getting in contact with a rioter, because this is ridiculous. And if I cant get unbanned, not like it matters, as im one of millions, but theres a good reason to quit league. I came to this game for enjoyment, not for people to curse at me all game because I died once. And yeah you can argue in this situation i should just mute him, but that is very unreasonable. I shouldnt have to enter every game I play prepared to mute every single player just because they can say something, rather I think the proof of seeing them say these things to people should justify the reason they need to be banned. I'm just at a loss of words right now, I really don't see how someone so extremely toxic, if not the most toxic player I've met in this game, just had the help of 3 other people to get me suspended, and probably got off free, even though he continuously targetted me and attacked me verbally. I know im not the only one who has suffered from things like this, there are people out there like this guy ruining this game for people, and even if its making League lose 1% of their fan base, i still think its ridiculous that these people are probably getting away with this type of stuff. I also want to add that nunu ended like 3/1/1, and probably didnt get banned because I guess doing good in a match is justifiable to convince others not to report you at this point.