Welcome to your new cyber family Didi.lost....
I am so sorry to hear of your heartbreak and stress, but you will find so many of us here have that too. We know the tears and the heartbreak that literally feels like it's about to kill us off. The horror of watching our AC go down the path of self-destruction is the most painful that I know and can make a mom feel like a failure and where did we go wrong.....however, it is not our fault. Our AC have minds of their own and make their own choices. My own sis told me recently, "look at how we grew up (which was very neglectful), and we didn't turn out that way." We did mess up when we were younger, but one has to eventually come to their own conclusions about where they want their life to go. We cannot do it for them. We cannot live their lives for them.
But take heart! This will start to pass as you start focusing on yourself and well-being. Self-preservation is so important right now.
My ex-sister-in-law has a DD who found her after she was given up for adoption many years ago. Her DD is glad to have found her as it does offer some closure in her life about the why's and where do I come from's. But, her true family is her adoptive one that she is most loyal to. Sometimes people just have to go digging of their own answers in their life and it's not to be taken personal by anyone else. Maybe, in time, she will come around again to her senses.
Sometimes people on that alcholic road have to hit their own personal rock bottom before anything changes and that can take a while. From my own experience, I had to be on hyperalert as to not get dragged down into their pit also by "trying to help". You wouldn't believe the thousands of dollars I have spent "trying to help" only for it to be up in smoke and it made the situation only worse in the long run as I enabled the behavior without even realizing it.
I am here now for my GD when she needs it, but my DD and SIL need to seriously get their act together and I'm sick and tired of it being at my expense. I might as well have flushed it ($) all down the toilet. People with addictions do not see things the same way we do....they only see what they can get out of you. You've said all you can say and it falls on deaf ears (don't I know it).
So don't be afraid to try to set some new boundaries dear Didi.lost. It's self-preservation time! Probably long overdue. Shake the dust off your shoes and focus on you now. It's ok to be there for the GC if you are able. They are the ones I feel for the most in my own situation, even though it's heartwrenching to watch DD travel an undesirable path.
Nothing wrong with texting your DD to wish her a happy birthday. You have nothing to lose.
Warmest thoughts to you as you travel through this unsettling journey. Hoping you find some peace along the way.