Is it all my fault

Lately I’ve been in a bad mental health space and texting my best (only) friend about it a lot. The thing is that she is also going through some stuff but I am trying to be there for her and any time I text her about my stuff I ask about her stuff too and open a dialogue. However it seems like she’s been cutting conversations short, not replying in an open ended way, or just not replying at all. I understand life can get in the way but we’ve talking daily for over three years and been friends for seven. Am I the problem? I don’t mean to trauma dump, especially bc I know she has some stuff going on, but I have literally no one else to tell and it’s eating me up inside. Now, I’m constantly questioning before a send a text, while I’m typing it, and after I send it if what I said was good enough and I’m only inquiring about her but she still isn’t really responding like she used to and I feel like the dynamic is different and she doesn’t want to talk to me any more. I need this friendship like I need air: I love her (platonically) and we’re very close and I don’t know how to address it without offending her or misconstruing the situation in some way. I’m basically sure I’m the problem but I don’t know any other ways to deal with the issues I’m having