I'm attracted to my......... ?

If you are close to your mother, sit with her at the kitchen table and tell her all of the things you put into your question. Tell her that you need her advice because it is becoming an obsession and is feeding your fantasies. She should not be shocked and may be flattered that despite the age difference you do see her as an attractive woman, but being mature she should see that she is having an effect on a maturing boy that she may wish to help curb. Your mother would be the best counselor on this problem you acknowledge (or you wouldn't have asked total strangers for advice)