It sounds like you're going through the stages of grieving. My advice is to see it through. It's great that you care as much as you do, and what I don't see is that selfcare put back into you. Not only do you deserve it, you need it, too.

There seems to be an off balance in your relationship, IMO. You've taken on the "saviour" role. I wonder if part of your loss you're struggling with has to do with feeling like you don't have a purpose, as you don't have anyone to save or fix..? This piece concerns me, especially when you're not putting that same attention to yourself.

Give yourself this time and space to grieve. Block her from everything so you're not tempted to try and connect.. or find yourself "waiting". Take care of you. Book an appointment with a professional even for just one or two sessions.

Don't get sucked into her world. She's 27 and feeling "old". That's her reality and not something you can fix yourself. She needs help. There's a lot of deep rooted issues she'll need to work through or you'll forever be in this rocky scenario.