... yikes

so im 14 and i started masturbating when i was like, 12 and it makes me feel guilty because my grandmother raised me from the time i was 8 to the time i was 12 and she always told me that it's disgusting for girls to do it and only guys are supposed to want sex and that its not like girls can get blue balls. shes a christian. i obviously never told her but it pisses me off because she makes me feel bad about it. i know i shouldn't but i do. any advice?