Is it normal to sex with aunt?

I have been having sex with my Aunt for 4 years. she is 38 years old, My ancle goes for work out of our city, so my Aunt call's me to sleep her house , she lives beside our house, when i startad having sex with her, on that night my auncle was not at home so i slept with my aunt , i used to sleep but on that night , i felt so heat ,than i asked her for sex , she said ok , then i did it, ön that time i was 18 years old ,now i'm 24, still it's going on, becoz of this , everyday there is fight in house, now it's became my habit to sex with her, but i want to leave ,but how ????