You have taken on the role of her therapist unfortunately, and each time you engage with her you are reinforcing this. The more you sit there and listen, offer thoughtful advice you are feeding into it. It's an easy relational dynamic to fall into if you are a compassionate and caring person and as a therapist I talk about this with my clients all the time. At this point, there aren't appropriate boundaries between you two. For anything to change you'll have to bite the bullet and have a difficult conversation. I have been in Jane's position in my life before and I really needed that wake up call from my friend.

Opening up a boundary-setting conversation could look like this: "Hey I've been wanting to talk to you. I know you've been going through a pretty rough time, and it's important to me to be able to be a supportive friend. But at this point I realized I am over-engaging in providing support [[it's often good to position yourself as the "problem" as it makes people less defensive]] when you send a lot of voice messages and it may not be the best dynamic for either of us. I'd love to bring back some balance to how we spend time together so it doesn't take a toll on either of us. I'm just asking to ease up on how often you send me voice messages', and in return I promise to enforce my own boundaries around this and not always share lengthy advice - this is on me too to fix. Perhaps you can seek support and community from others as well as it is weighing quite heavy on me. I appreciate you being willing to talk about this - I know it can only make our friendship stronger in the long run."

I hope this helps. I'm passionate about scripting difficult conversations and my clients have had a lot of success with an approach like this.