Have a friend who I’ve known for around five years - initially work colleagues, friendship was fairly superficial for the first couple of years and was mainly work interactions/lunch breaks.
Around three years ago we started spending more time together out of work - a few holidays, nights out, the usual. She’s confided loads to me and always told me how I’ve helped her so much/give such good advice. I did always get the impression it was quite one sided - but didn’t mind hugely as we had a great time, and I could see her almost like a younger sister.
However, over the last two years I’ve sensed quite a lot of bitterness / jealousy under the surface (although I have no idea what she could be jealous of) but everytime anything good happens to me, she brings a negative on to it. She only really seems to want to talk through things when she thinks I’m struggling or having a hard time - then she magically appears everytime without fail. It feels toxic.
Can’t give too many details as they’d be extremely telling! But one was me really struggling financially - she’d ask what was wrong, making out she wanted to be supportive but then as soon as I confided anything in her the response would be awful. Along the lines of ‘oh that sounds difficult. On another note, I’ve just had a promotion and can you help me pick where to go on holiday/which new car to get?’ Believe it or not, really that insensitive.
That wasn’t an isolated incident either, I was struggling with body image/losing weight due to meds I had been on and within about five minutes she’d turned the conversation into how she loves her figure and is so glad her body doesn’t hold on to extra weight... 
Even worse; when I have something good going on or improving she really tries to put a downer on it. Example: ‘Had a really good day, started at my new job and feeling positive about it’ her response: ‘oh that’s great! But the only thing is there isn’t much career advancement in that, it’s definitely not a job I’d be happy with but perfect for people who have quite inactive lifestyles’
Haven’t dealt with many people like this but I really want out. Around a year and a half ago (possibly a bit longer) i tried the distancing method but it just made her redouble her efforts to be in my life - relentless messages/social media interactions, trying to be as fun and engaging as possible. It’s not really an option to tell her how I feel because I know she will cause a HUGE drama about it, tell other people, etc. So I’m not sure where to go from here 
. I can quite literally go weeks with minimal contact and she will still continue with the relentless attempts to contact me. Any advice - should I just go NC despite the shitstorm she’ll attempt? She’s also wiggled into my work life and tried befriending my family members strangely which is making it even more difficult to shake her off.