Feeling used, problematic friend (Long vent)

I don't want to be friends with her anymore. She can't stop writing negativism in her messages, claiming that her fanfic has low reads, that no one is interested in her ship, that there's no one of the fandom we are in that wants to talk about her fav character and so on.

I always explained to her that numbers are not important, because it is only content that makes YOU happy, and it would be enough to share it with your closest friends and have a joyful conversation. (Besides, let's be honest, you can't pretend a big audience if you write for a dead fandom). However, she doesn't understand. She is always complaining, as if she needs extreme attention, all day. She needs to be validated by everyone saying "oh, but your content is so cute", and so on.

I really noticed she has these moments of attention seeker, and this is worrying me, because she might use her social media in not the correct way, complaining and making a fuss over everything. When I can tell she is in one of these episodes, she makes tons of posts of social media. "I am going to delete my blog, no one reads me. No one likes my stuff", and so on... She even spams in a personal *** server we have with other two girls, of course, trying to make us compliment her. Oh, and by the way, she made another server where she apparently invited all her important people. This gave me a huge red flag, because she always pretended people to talk there, all day.

Now... You are wondering, if she finally meets someone from the fandom, she will be happy, right? Wrong. She always has a problem. She always talk bad about these people, and she wants me to follow her game. I have no drama with any of these people, yet she just wants spice since someone shares her f/o or it's a friend of one of these someones (hope you understand this part...). I don't want to talk bad about people I never had a beef with, I don't know if she's aware that this is wrong. She finds a problem in every single detail, like "this person never played the games", or "why are they just switching to the most popular characters". This is pissing me off, honestly, because here we go again with her complains...

Since she complained a lot that no one arranges a gift exchange dynamic within the fandom we're in, I offered myself to make one. The gifts were presented yesterday - drawings, fanfics and letters. It was so cute. The person who worked on a letter to her asked me a lot about her OC. I can tell this one blud put effort! However, she cried on my DMs saying the letter is too meh, also posting on Bluesky that "the letter she got left her with a bittersweet taste". And when I was on the server with the other two girls, showing the drawing I got in another gift exchange, she quickly appeared, crying that she didn't got one and I was like... ._.? I turned into a clown. Literally I arranged a dynamic for her and she doesn't show a hint of gratitude.
(she always complains her gifts, btw. Even if she commissions, she always has a complain. Nothing satisfies her, and the letter fed me up completely)

I don't want to be friends with her anymore. I am going to exit the server. If she wants answers, I will tell her everything in the best way possible. There's no way an adult woman is acting like a teenager, seeking attention through victimism. Her harsh past shouldn't let her act like this. I am aware of her past, her traumas, but I don't want to be the one that cheers her up anymore, because she doesn't do the same in the end. We used to joke that she's the extrovert person who adopts the introvert (me), but I think the real thing is "I only pull your strings when I need your validation".