Welcome. I am so glad you are here. There are a lot of stickies at the tops of this forum. When I first showed up here I read and read and read. There is so much useful information.
No one can really tell you what to do. What I can say is you didn't cause this, you can't control it and you sure can't cure it. You can help yourself though. Nar Anon (or Al Anon if you can't find an a Nar Anon). Ask around, you will find meetings where you feel comfortable taking your child too if you need.
Thank you for posting. Keep coming back. You will find wonderful support here.