It's late at night here/early morning and I often wake up on purpose go meditate and to enjoy the stillness snd quiet before going back to sleep. So I saw your post.
Nobody has all the answers here. We share our experiences and our life experiences bias our advice. But we do all have in my opinion good things to say and we all care deeply for everybody, snd the passion in our answers come through. Here are MY thoughts.
My gut tells me that if daughter moves in it won't work out anyway. Most of us can't live for too long (nor should we have to,) with constant abuse. I f you like and are able snd want to, I would maybe offer grandchild s safe haven, but tell her she is 30 years old, you can't live,/rescue her forever and that you need her to get her life together with community with resources, not mom.
We do not have to put up with anyone's abuse, and, yes. Thst includes our grown children who need to mature to their adult age or learn how to best live on the streets because eventually they will end up there if they don't get help ,,,,,,(only they can truly put their heart and soul into therapy and growth). If we make them go as s condition of ongoing help by us in any way, they are likely just going through the motions to get the roof, the free babysitting, the lack of need to mature, our money... to stay mentally a child.
And you deserve peace in your house, your sanctuary.
Does she work? Use drugs maybe,? Stress you out? Is her presence one that makes you tremble in advance,? Has your "help" ever really helped,?
Do you value your own life? Do you have other loved ones who treat you with kindness and respect? Flock to them. They deserve your kind heart because they offer you a healthy relationship without stress. They can love you back. This is a priceless gift.
I learned this trick recently while trying to learn to trust my intuition:
If you have to ask yourself if something is the right thing to do your gut is telling you it is not. You know confidently and without hesitation if something is right.
Think of eight year old grandson. Does he need Mom there?
You may want to look up borderline personality disorder to see if it fits. If so perhaps read the book "Walking on Eggshells." It's easy to find. It is very reassuring and helpful.
These are just my thoughts? There will be much more input and wisdom. I suggest you check with your gut and do what it tells you is most likely to work out. 30 isn't a child and you earned your right to let go and have peace. It is yours to claim. Or not.
I wish you some peace and if this post helped even a little, I am glad. Hugs and love. We are all with you, holding your hand without judgment. In the end we must do what we feel is the right path for us. There is no one way.