Hey there Pats12,
Congrats on finding the answer to this situation on your own. Understanding the fact that you are being used for attention and discovering that it is not an authentic relationship/friendship. The easiest way to handle this would be to once again state how you are having difficulty contributing to the friendship. As you mentioned before when you called her out on her actions, she began to get defensive and projected it on toward you. Avoid this at all costs the next interaction.
The next time you see “M” let her know of the difficulty you are having and let her know that you are not able to handle it. Slowly after some time begin to break contact with her and start living your life once again. Of course she may do you the favor and after you let her down easily, she may not want to talk with you any longer because you showed actual human emotions and she won’t be able to handle it aka “use you”. I went through what you’re going through as well with girls in my early 20s. After some time I got tired of all the games and hidden agendas and went back to being direct and honest to the point. They are out of my life, no contact and I’m much more at peace.
Hope it all works out. I know it will.
Thank you and take care
-AP85