Toxic friend? Need advice

I need some advice from this community. This story can be very long, but in a nutshell I have a friend who historically I feel takes advantage of me. I have been friends with her for around 7 years and throughout that duration, I have found out stuff she has said about me behind my back, have witnessed firsthand nasty texts she has sent about me(she showed me by accidentally on her phone), and just overall have encountered small things that I didn't think about at the time but have seemed to always add up to larger fights. She got jealous when my boyfriend and I got a new dog. So much so that when we both went to a mutual friends birthday party, she blatantly ignored my boyfriend and I and told me she didn't want to talk to me. We ended up getting into a blow up fight over her being so passive aggressive. When we met weeks later she basically admitted she felt like I wasn't hanging out with her as much as I used to and giving her my time. She has always been nasty to this boyfriend (who is now my fiance) and she continues to follow my ex on instagram who put me through emotional turmoil for 3 years. She brings him up often and even bumped into him two years back and divulged personal information about me and my new relationship to him. Fast forward to my birthday this past year. She did not send me a direct text to say happy birthday but instead only wished me one after a friend of ours pinged me on a group thread that my friend is on. I responded "thanks!" to the first friend but not to her and she followed up with "You're welcome for my wishes too." At this point, I had enough. I never responded and deleted her texts and just never reached out again. That was October. It's now June and my boyfriend just proposed to me. I really thought once she saw the photo on social media she would reach back out at least to open the lane again and congratulate me but instead I have heard NOTHING. I have NO idea what I did to this girl to make her so mad and ghost me for this long. I am starting to think she is just a selfish, narcissistic person. I should also add, my mother has stage 4 breast cancer she is well aware of and I informed her of my dads heart surgery that occurred right before my birthday - so none of that stopped her from acting out at me in this way. What is the deal for real? How would you guys deal with this? Her and I have VERY CLOSE mutual friends and literally live in the same neighborhood, so I am just waiting for the dreaded in person interaction.... I should also note for her birthday this time last year I not only brought her flowers but helped pay her bar tab.

She sounds like she is much less capable of empathy and much more selfish than you. I have no doubt she likes you and values your friendship. It's just that you both have very different concepts of what friendship is. This girl sees the world and your relationship veeerrry differently from you. I think you could still be friends with her but being close friends sounds too much like hard work to me. Hard work for you at least.