Hey Blossom, glad to see you again. Hope you and little Blossom are, well, blossoming. I definitely learned codependency from my mom, and to a lesser extent from my paternal grandmother. Since I no longer have active alcoholism in my life on a daily basis, most of my struggles today involve non-recovering codies- my mom and brother and also my ex's parents and wife.
I've found my Alanon program to be immensely helpful with that. I can be grateful that I'm no longer living my life that way and can enjoy my relationships with different people in the place they're at rather than wishing they would just get with the program and get into recovery for themselves. I even quit sending Alanon literature to my ex's parents!
I still struggle with feeling responsible for and wanting to caretake other people's emotions, and that is a harder struggle for me, one that I'm not sure I'll ever be totally free from, especially in my close relationships. I have to work hard to separate my stuff from other people's stuff and make sure I'm not taking on their emotional burdens.
If you mom is jealous or upset with you and LB's relationship with LB's "other grandma" that's her responsibility. I know how uncomfortable it feels to be in the middle of something like that, but you sound like you're handling a tough situation with grace and dignity. Good for you.