I am sorry that your daughter let you down it’s so confusing and frustrating. I think you received a lot of good choices you can make for yourself and for your granddaughter.
Al-anon -
Keep posting here - and venting, read the posts at the top of this page especially the one about “What addicts do”. Gain knowledge of their trails when they are in active addiction.
Most important, be gentle with yourself as you are learning and it takes a while for that knowledge to actually sink in. We often think “our addict” is unique, different then what others are posting about. Your daughter SHOWED you who she really is when in active addiction learn from this experience so moving forward you are better prepared to understand issues.
((((big HUGS))))