Welcome to this most special place.
Like you, I struggled with letting go of my daughter and the outcome. It was humbling to accept that I had no control over her or her choices and that I had to focus on taking care of me.
I too was no stranger to blaming myself, which goes hand in hand with embarrassment. In our society, parent ego is often tied to the choices our children make. And so, when our children make horrible choices, we feel responsible. If only we could love them out of addiction....then none of us would be here.
Letting go is acceptance that we have no control over the outcome.
Nothing wrong with letting your daughter know that you love and support her recovery, at such time she chooses to embrace it. Getting caught up in voice mails and text messages tends to sustain your belief that you can control her and the outcome. This sort of thing sets you up for anxiety, disappointment and anger which can take over your entire life.
May I suggest that you acquire a copy of Codependent No More by melody Beatti. You can pick a copy of at your local library or used on Amazon.
It can make a difference, if you are open to it.