Nar-Anon Chat™

This is my first time on this site. As most…I'm feeling lost and helpless and exhausted from the chaos.
I've been dealing with a daughter (now 33) who is addicted to Meth. She has had had a few periods of sobriety but nothing lasting. She's been using for about 16 yrs.
I just need to find some support. Hoping to gain wisdom, knowledge, and support. Trying to learn to set boundaries without feeling like I'm turning my back on her. Getting my heart and my head on the same page is almost impossible. I know in my head I am powerless but heart says…you have to let her know your there for her and you can't turn your back on her like the rest of the family.
Thanks for reading.