I don’t think your mother thought about race when she married your father. Their relationship fulfilled some purpose or void for her at that point in her life.

I’m sorry you didn’t have a chance to learn about your heritage. That must be really difficult and confusing growing up. As far as tanning is concerned, I believe Indians fall into the category of being racists within their own race. Obsessed with “fairness”/ light skin, they discriminate against other Indians who are darker skinned. Not excusable, but your mom is not alone in being racist.
Perhaps, it’s not too late to learn about your Indian side of the family?