Codependent friend?

Hi, I hope all of you are doing well?

My anxiety, especially around my phone, is skyrocketing currently.
I have a friend, which I'm close to for about 10 years already and I really love her dearly, but currently I feel like she is starting to depend on me too much.
She isn't mentally healthy, just like me, and has started therapy for a while as well, so I was kind of hoping it would start to slow down a bit now that she has support from the outside too. Sadly I was wrong.
Now, don't get me wrong, I think it's absolutely fine for friends to depend on eachother and I have a lot of friends who come to me to talk about their problems (They know I won't judge them since I have a lot of problems myself). But with her I feel like I'm starting to constantly just listen to her problems, calm her down and give her (asked) advice (which she doesn't follow - why ask in the first place...).
I don't really have the normal type of friendship with her anymore. We don't just hang out to have fun but instead always discuss some kind of problem.
I can rely on her as well and I sometimes do, but I try to keep it on a level to not burden someone and I feel like she doesn't have that boundary anymore around me. My screentime has gone through the roof because I'm expected to answer when there's something going on or when she's alone after work and needs distraction.
If I say something along the lines of "Sorry, I don't feel like texting right now" it's usually met with any form of "It's okay. I'm used to being alone at this point" - maybe not in those words, but the meaning is always the same. Which obviously makes me grab my phone more than I want to, to keep her from being alone.
I have a lot of struggles I'm dealing with myself. Especially currently where I'm working really hard on breaking all my bad habits formed by mental illness, to start making bigger steps in healing. So my energy levels are usually really low at the end of the day from all that internal work I have to do. Seeing her messages pop up makes me even more exhausted currently. I honestly don't like it. She's a nice person and a good friend (when her mental health is fine), but I just don't feel comfortable with that "personal therapist and companion" role she's putting me in.
I haven't even given my ex boyfriend as much attention as she's demanding from me. And I'm really tired of always having to listen to negative things only. I'm training myself to be more optimistic (in a realistic kinda way) but I have to listen to negative self talk from her all the time. It doesn't make it easier on myself.

I'm kind of lost on this one.
I don't know how to handle this situation without breaking the friendship. There's a reason we've been friends for 10 years and I actually really like her. It's just getting too much. I have anxiety bursts whenever my phone shows a new message notification.

Has anyone else been in a situation like this? Do you have any tips on how I could handle it? I'm someone who likes to talk things out, but I can't really handle the way she reacts to me putting my phone away already, so I feel like talking about that personally isn't an option I can deal with right now (especially since, like I said, I already have so much I'm working through myself right now and have barely any energy left at the end of the day).

Thanks for reading all of that. It's a long post, I know.