Worse newbie experience so far from another player...on my team..

today i was doing PvP games, and mind you i have only been playing about 2 weeks or so, so i am still learning, terms, ect...but today took the cake. this one guy was playing Tahm ... and he was jungling, and when we went to go start, i went mid, farming the minions, poking at the other guy. and he suddenly starts rudely screaming in caps for a "leash"....now...(in IRL and other IRL....stuff..) i know what leashing is..lol....but i was unaware what it was meant in LoL. so i asked him what it meant. and he told me. so i left my lane when i sent the guy i was poking at back to heal, and helped this Tahm kill the wolf pack, and went back to my lane, i seen he lvled so thought he would be ok.... i.was.wrong. well, he died a couple times in the jungle....not my fault, i was busy holding off the mid lane, and the others where busy too in their lanes. and then he forgoes the jungle. and im here thinking, ok, so maybe he decided to help in mid....i was soo...so...soooooooooo......wrong. he ate me. right as i was recalling to go heal. and spit me out at the touret and had me killed. then as i respawned, he was waiting for me at the first touret, ATE ME again, and i tried to click to get out, but i im not sure how, and he spat me out, into 3 of the opposite team players. first i thought...ugh...wth... maybe mistake? nope....he repeated this....then i told him to stop, he refused, and started to do it to poppy (and the others!) when she came to try and help defend the mid lane. by this time the other team had caught on the Tahm was feeding them. and they where all barreling down mid. why is this allowed? i realize its one of his abilities....but why is a player allowed to abuse it? we asked him to stop, over and over, and asked him why he was feeding the other team. he claimed, we didnt help him....but i did....! he claims i didn't. and started swearing at us, ect. he ruined the game match. we HAD to surrender. he fed them so much no way we could have come back from it. we reported him as well. as a new player, i do not understand why there is no inMATCH reporting system...or a way to kick a player out that is being so cruel. now, im no kid...ive dealt with bullies, but this was ridiculous. as a new player, worst experience ive had so far. heck even the bots in ARAM i don't mind too much, if we win...lol...but in game bullies abusing a champs special, should be a way to instantly vote/kick. sorry this was so long, it was just upsetting as a new player. most of the people i have met have been nice. even in opposing teams. but i guess sometimes you get stuck with a toxic, rotten broken egg. i did block him as well. i really hope Riot deals with this player. :(