Intentional feeding and the only excuse is lag?

While i was playing on my 2nd main account, my team came across this top riven. When she lose her laning phase with Yasuo. She began to start feeding and trolling entire game. Then start to spam entire chat with lag here and there non stop till the point it got us raging. I had no choice but to mute her as even other team members also did so. Imagine the chat spamming lag (with CAPS on) throughout the game. Even came to KS our kills as we did all the damage. Surprisingly, she didnt say lag when she got kills but only when she dies then blame on lags. This is the kind of player, i really had to report. If not, im letting her go too easily.