Close friend has been ignoring me for weeks ?

Hi,
One of my closest friend (we have been friends for the past 20 years) has been ignoring my text for the past 6 weeks. By ignoring, I mean that she avoids to open my latest text on WhatsApp so it won’t appear as ”read”. But I can see that she is online all day long, so I know she is aware of my message, and I also know that she could also see the content of it when she chose to ignore it.
This latest text is a request for her to write a letter extremely important to me on a legal matter, that she agreed to do a few days before the text, and because I know she is super busy, I wrote the letter for her, sent it, told her she was welcome to change anything she wants if needed, and then if she could please print it, sign it and take a picture of it to send it back to me. This letter is a genuine statement so nothing compromising or uncomfortable for her. I wrote a lot of letters for her in the past few years when she was dealing with family issues with insurances and stuff because I’m good at it (in my native language) and she would often rely on me for that. This is the first time I request a letter from her.

I’m pretty disappointed in her for a few reasons.
First, I live abroad and because of the time difference, we don’t call but we regularly leave each other voice mails on whatsapp (a few times per week) to update each other with our daily lives. In the past year, I noticed it became more and more about her and less and less about me, with her constantly ranting and talking about her life, but never offering any reaction to what I would share with her. I suspect she did not even listen to some voice mails that were about me, and would only care about the ones where I was reacting or sympathizing with what she was going through.
I did not think much about it at first as it seemed she was entering a new phase of her life : meeting a new group of friend, changing job, dealing with a difficult teenager, dealing with two potential suitors. But things started to settle in her life and it was still all about her. At some point last summer, I went through something extremely difficult regarding my sister health (she knows her pretty well and likes her), and I mentioned it to her, twice. Twice she ignored it, no reaction, not even a kind word of sympathy. She then proceeded to say that ”she was being a terrible friend to her ex boyfriend because he needed to talk about his challenges and she was just ignoring him because between her new boyfriend and her new friends, she was always busy and did not have time and felt terrible about it”. I took that as a hint that she did not have time for my problems either, but she did have time to talk about hers at lenght in the regular voice mails she would still send to me. She also regularly took time to tell me all about the drama her new friends are going through and I never met these people.

I honestly don’t like and don’t recognize the person she has become in the past year. She neglects her daughter and kicked her out from her home when she has been crying for help for months with bad behaviors, she neglects her cat, she neglects our friendship and she spends all her time partying in the week-end and seems to feed herself of the drama of her new community.
What hurts the most is that she put me at the same level as one of her older male friend, who is a pervert making her uncomfortable most of the time and never respecting her boundaries, and despite me encouraging her to cut off ties with him, she keeps seeing him when it’s convenient for her/when she can get something out of it, but will leave his messages unopened for weeks when she does not feel like dealing with him.

I’m tempted to delete her number and move on, because I don’t see a way back, but my boyfriend is advising that it would be a shame to throw through the window such an old friendship with one of my closest friend just because she is going through a teenager phase again (we are late thirties).

Thoughts ? Thank you.