Your post made me happy and sad. Sad because I felt your pain and your helplessness. Happy because I too am new here , but I know already how the wonderful people on this site will help you to cope with the feelings you have now, and will have in the future. They have helped me move forward so much already , even though I have barely started yet on my journey.
Be kind to yourself, Ive learned that already, you deserve happiness and are not your mums keeper. Yes you love her and want to help her, but she has to do the hard work herself , for herself. You have your own hard work to do, for yourself.
Lots of love and a huge hug coming your way Megan.