Upload dating my my friend crush is always makes cum

I feel ridiculous that I have to rant about this because I always keep my feelings to myself but I really need to talk. 

So this just recently happened, i found out about an hour ago and have been on the verge of tears ever since. my best friend is dating my crush. lets say my crush's name is John. okay so i started liking john about 4 years ago. Im conviced he is my first love but ive always been too shy to admit it to him. My best friend knows about how I feel and has always been supportive of me confessing to him. A few months ago, we all started talking in a group chat and i noticed that my crush's interest and my friends interest are very similar and theyre both fairly attractive people so i was already a bit jealous at that. Just a few days ago I found out my best friend has been messaging John in a private chat and theyve been talking very often, way more often than me and my crush have ever talked in these past 4 years and John seems to be very open with my friend. I asked John about a year ago to text me and gave him my phone number and he even gave me his because I was attempting to get closer to him, but that never worked out. (i know im bitter))) Now though, John and my friend have been texting, private chatting and even flirting with each other in public posts on twitter. I also noticed my friend has been pulling away from me lately and rarely likes to sleepover at my house which is strange to me because we would have sleepovers every weekend. My friend doesnt talk to me as much anymore and when she does I always learn new things about John because thats all she talks about. I told her about a week ago that I still have feelings for John and she said "oh, still?". I viewed it as her just teasing me but now I think it had an entirely different meaning to it. Im sorry this is such a long post but i have nobody to talk to, all of my other friends live states away and are asleep and i feel like im gonna explode if i dont let anything out. 

So back to an hour ago now that you have a basic backstory, i found out through my other friend in our group chat that they are dating. I didnt hear any of this from my best friend at all. Im so shocked and hurt that she would do this, after 7 years of friendship. If she had feelings for him she could have told me, it wouldve been better for me to hear this from her rather than our other friend who my best friend actually has or i guess HAD a crush on (shes bi btw). Im so upset right now and i feel so betrayed. I know i sound so selfish but i have the deepest and most sincere feelings for John and he was the first person ive ever felt this way for. I already have trust issues and feelings of insecurity and being unwanted and this all just confirmed everything for me. I dont know what to do, i want to be a supportive friend but my anger and jealousy is so bad. A part of me feels like she did this on purpose, just to hurt me because she is a very spiteful person like that, ive observed her over the years and the way she is to other people is terrible, shes spiteful and an asshole. I dont know why i thought she would never do this kind of thing to me, she always said she valued our friendship more than anything in the world, but now I dont know if her words were true. 

I need some advice on how to deal with my emotions because all I have on my mind is revenge and a way to hurt her the way shes hurting me. I know i just sound like a bitter, jealous bitch but im really just sensitive and heartbroken.