Thank you for contacting JustAnswer.
I am sorry to hear about the problems you are experiencing with your daughter. Many people will use alcohol to try to "self medicate" to dull the emotional pain that they are feeling. You may find the following link for Alanon to be helpful in offering support for family members of those who have drinking problems: http://www.al-anon.alateen.org/ This may help you to understand the issues that are occurring. Meetings can also be helpful to get support from others who have been in your shoes.
It sounds as if your daughter may be avoiding facing her feelings and may not be able to feel them in a safe way, so she may use alcohol to avoid them. One of the hallmarks of addiction is to deny that there is a problem and to avoid taking responsibility. While you can't control what your daughter does, you can be very clear with her that you love her, you are concerned about her, and that you believe that she has a serious problem with alcohol. Sometimes it is helpful to have multiple family members and friends get together to have an "intervention" to let her know how serious your concerns are. Addiction specialists in your area should be available to help you with an intervention if you decide to go this route.
Additionally, one thing you can control is to stop any enabling behaviors. This is a difficult thing to do but is the kindest thing in the long run for her. That means no more financial support, no bailing her out, no making up for her mistakes, and instead using tough love - letting her know that you care about her but you will no longer help her out. Of course, you may still want to make yourself available for her children as much as you are able to. Unfortunately, you can't control how involved her ex husband is with this problem either. If you feel that the children are in danger then you could contact the authorities to make sure that they are safe.
Since you can't change her, one of the things you can work on is you. Remember to take care of yourself by a focus on healthy activities such as exercise, eating healthy, hobbies, time with supportive people, etc. Above all, make sure you give your daughter, your grandchildren and yourself unconditional love. I wish you the best with this difficult issue. Please let me know if I can help further.