not sure if i understood correctly-you were adopted and the mom you are feeling guilty about was your birth mother? don't feel bad about not going to see her. you were young and how you felt and what you did was perfectly understandable. your mom would have understood too. the fact that she kept a picture of you as a baby shows how much she loved you so i know for sure she just wants you to be happy. it's not weird that you feel worse over her death than your adoptive dad's because there was no closure. maybe one day you can reconnect with your brother and talk about everything.

when my mom died, i felt guilty for many years but i finally realized she would not want me to be unhappy so i let go the guilt. i hope you will be able to one day too.