How can I stop feeling guilty when my Mom pushes all my buttons?

I have 3 siblings, my mother is only able to guilt me. I am the baby. My mother and I have a very close relationship. We even went to nursing school together and graduated together. My brother tells me, we are hooked together at the hips LOL. She uses that love to manipulate me. I get mad at myself, because I know she is doing it, yet I continue to allow it. HELP! How can I change this behavior without hurting her feelings or feeling guilty.