I’ll come back to your question about anything you can do now. But first, I want to come back to what you said yesterday about not being able to separate her pain from yours and getting anxious when around her. It sound like you may have some traits of a highly sensitive person. www.verywellmind.com/highly-sensitive-persons-traits-that-create-more-stress-4126393. It is possible your dd has some of the traits of a highly sensitive person too. Perhaps you also have traits of an empath. www.healthline.com/health/what-is-an-empath.
The two of you together are working against one another and dd has basically trained you (and you have allowed it) to do exactly what she wants, to be exactly who she wants you to be. But you are not who or what she needs you to be for her own personal growth. And it’s great you’re now recognising that. Because you are absorbing so many of your DD’s emotions, therapy would really help reduce this and I see you are considering getting some.
So coming back to what you can do now. You are going to need to put boundaries of steel up with your dd in a loving and caring way. I think that’s going to be tough without the ear of a therapist. I’m sure mumsnetters will willing help you but the first thing I would do today is to find a therapist.
Even if you start working on this today, you’re not going to have a quick fix on this one as you’re having to completely reframe the relationship. And going for quick fixes are what has ended you up in this mess in the first place. Both your dd and you have gone for quick fixes to feel better in the immediate without thought to the long term. You can get started now. But having a therapist on side will be fundamental in giving you the support and space to continue as you will get a lot of resistance from your dd and in the long run, if you put it the hard work it will really benefit you both.
I’ve done a lot of work on boundaries myself. I suggest you Google “setting boundaries with an adult child”. There’s a book on Amazon with this title with are mixed reviews. I had a glance at a few articles on the Google search results and a lot are not what you’re looking for but here’s one, which seems more helpful. www.empoweringparents.com/article/rules-boundaries-and-older-children-part-ii-in-response-to-questions-about-older-children-living-at-home/.
I also googled setting boundaries. Now this is the sort of thing recommended for toxic people. The dynamic in your relationship with your dd is pretty toxic, which is why I’ve included it here. Just be aware it’s harsh as not written for parents of children. But I think worth a read so you can recognise your feelings and maybe glean some ideas from it and adapt them in a loving and caring way. livewellwithsharonmartin.com/set-boundaries-toxic-people/
What your dd really needs now is some tough love, to be set adrift a little so that she can find the resources within her to work out her own life. And once you get therapy (with the right therapist), your communication will change and your conversations will naturally turn to teaching your dd what you’re learning. You’ll be able to offer her decent advice on boundaries, she’ll understand parent and adult child roles, expectations of behaviour from boyfriends and how to treat herself and others with respect and dignity.
Bottom line, you cannot change your dd. You can only change your behaviour and reactions. And once you change, your dd will be forced to make changes.