Best friend betrayed me?

So a few days ago I received a request from a page on Instagram. I didn’t think much of it because it looked like a normal page. This page sent me a dm and started harassing me about my bf. Claiming they wanna rekindle the relationship and all this other crazy stuff. Whoever was behind this even called me multiple times threatening me over him. He has this one ex that for some reason hates me for no reason whatsoever. I don’t know her personally, but I only know of her because my bf found her creeping on my social media and I had no idea she was following me. I ended up blocking her from my social media because I felt it was odd that she was keeping up with us. This person lives back in his hometown that is 2 hours away. He no longer lives there. This girl has also made multiple fake pages trying to follow me to see what we are up to. I deny & block everyone. So back to the fake page, I noticed the fake page was literally following everyone my best friend knows. I found it a bit odd at first but now I’m starting to think she might have something to do with this. I also noticed that while this was happening she was awake and she’s never awake at the time this was occurring (3am) so I found it very odd. Also to mention his ex follows none of those people on ig. I checked in order to see if maybe she had something to do with it. I asked my best friend if she had anything to do with it and showed her all the proof I had & she got very defensive and upset. And it’s like if you know you didn’t do anything why are you getting so defensive? She also stopped texting me and has not responded ever since. And also to mention my best friend knows his ex. They used to go to school together & she knows very well that girl does not like me. I just can’t believe my own best friend might have something to do with this. She’s currently broken up with her boyfriend. Idk what to do or how to approach the situation anymore. I feel very hurt knowing someone is trying to break us up. Any advice will be helpful ladies & please no rude comments I’m already going through it.