Children Of Divorced Parents Support Group
This community is for the children of divorce, both for adult children who have lived through a divorce as well as parents concerned about the effects of divorce on their children. Share your story and get advice in this support group, where there are others going through similar challenges.

My strong suggestion is to seek a school counselor who can direct you in some way to find tools and strength to not be the listener to inappropriate worries and stories from a parent and redirect you to find tools to avoid listening or mom using your time and heart in such ways.
It is not a child/teens job to fix a marriage or hear sad stories that do not end, it creates much anxiety and is out of bounds with the relationship. You do not have to be her counselor, but just her daughter.
Finding tools, means when it starts you have courage to redirect her to appropriate sources for counsel and healing and that you can not be that person for her, as it affects you detrimentally to know you have no power to help and no life experience and that you need parenting right now.
It is hard, it is your mom and you can be respectful about how you approach this. Another suggestion is to gain help from a trusted family member to help guide your mother to outlets and to help her see you can not be her adviser and counselor. Sounds easy on paper, but it is not, but it is worth it to set those lines, so you and she can have a good mother daughter relationship. While you should strive to be a good teen (does not mean you have to be perfect, but try and work at growth, it is not your job to fix such huge things for your mom. Some small things yes, to listen, but not marriage and divorce things, unless it is to say a decision has been made, then you need to know..... All the best....