Sharing Our Innermost Thoughts

I really dislike my best friend, she’s rude, makes fun of me and embarrasses me in front of others, she’s the kind of person to snap at people anytime just bc she’s in a bad moon, which she’s in everyday basically. She complains about people asking her why she ghosts them, why she’s suddenly treating them badly, people, just like i would too if i didn’t know her so well, wonder if she’s mad at them to what she always answers by just staying it’s nothing personal, she’s just not feeling well, she’s always mean and tries to justify it all of the time. She thinks the world revolves around her and only she is struggling, she has no idea what i’m going through cuz she’s so caught up in her head she never listens. She never wants to hear my opinion even when she’s the one who goes to me for advice, she only wants me to say what she wants to hear. She’s in a toxic relationship with a guy who’s cheated on her 6 times yet she puts him before anyone else, even before her friends who are actually good to her. The only reason why i haven’t cut her off and removed her from my life it’s bc we’ve been best friends for 13 years and she feels to familiar to me, i still don’t understand her and she makes me feel extremely frustrated all of the time but it’s weird being without her, im too used to have her around, i feel bad to let go of someone whom i’ve grown up with, i don’t like changes and she’s just like my daily routine, i always go to her, and i’d take years for me to find someone else like that. What should i do? i’m tired of trying to keep her around and idk if it’s the right thing to do anymore, yesterday was my bday and she didn’t even say anything, is it silly that i feel sad bc of that?