Is it normal to be attracted to my mom?

i am 19 years boy living with my mom. my two sisters are married and my father is dead.my mom is black with big fatty body. sometime she sit on the couch in sitting room and she read newspapers while putting legs on the table and not wearing anything inside apart from the gown and she use to sleep on the couch in day time especially in weekends without caring if me her son is living in same house and the bad thing she open the legs wide and i see everything ( i mean her genitals ). because of her big thighs and butts when i see her i become so attracted and i can't touch her and i never touch or tell her. what can i do?