Is he obsessed??

Long story short. I met this guy through a game we both play called (LoL). We spent everyday talking since we met but I began to feel uncomfy because he started to rush things way to fast. I liked him but that quickly went away after he said I love you after 3 months of knowing each other. Then I told him I didn't feel the same anymore because I felt like everything was rushed, pressuring me to call and constantly asking me out even though I don't date online (unless I met them) I told him about how I felt and he ended up being really cold and rude to me, telling me to stfu and kill myself, he also refused to take no for an answer. After I laughed it off and went on with the convo I sent him a smiley

face, he tells me if I ever send him a smiley face again he's gonna find me and "slit my throat" then continued to ask for my address then later said it was all a joke, then I wanted to unfriend and he got all nice again, should I be worried??He says he's gonna wait for me and continue to contact me, I'm 17 and he's 21