i need your help :(

guys I need to talk to someone but I don't know where to go. so I'm going here. over the past 3 months   I've been getting cyber bullied...by my internet best friend : ( it all started back in march when some girl on instagram started having a go at me for no reason. she pointed out everything I'm insecure about and made me think that suicide was the best option. she carried on for 3 weeks until instagram deleted her account. I was so glad she was gone and my internet best friend helped me be happy again. I told her everything! what the girl said, how it made me feel, and how it all started. She was the nly thing that made me smile. then 2 weeks ago she just came out of nowhere saying I was a fat evil bitch who should go throw myself out of a window </3 :( !! she kept saying stuff like that everyday and still dose. this morning I woke up to a message saying "hells waiting for you bitch! hurry up and die already because nobody likes you!!" I didn't do anything to her but she says all that stuff! I don't know what to do :( I block her on instagram but she keeps making new accounts. its the same with snapchat facebook tumblr and twitter!! How do I get her to stop :_ _ _ _ (

that's it so
problem prone going back to the real world :( xxx