Is it normal to masturbate thinking about my aunts feet?

So iv never felt any sexual attraction or had any fantasies ahout my aunt(dads sister) EVER. But recently i was visiting her house and she was wearing flip flops. Iv always had a foot fetish and have never been ashamed of it and have fully embraced it, but when i saw her feet in those flip flops i found that i just couldnt keep my eyes off them, i looked away beacause shes my aunt so i shouldnt be thinking that way about her but i just could not stop staring. I was getting really turned on and it got so bad i just has to go to the bathroom to relieve myself. I thought about sucking her toes and came in only 30 seconds. Iv felt so guilty ever since and i know its just so wrong to think in a sexual way about my aunt, but is it wrong if its purely her feet im attracted to? Iv been thinking about her feet a lot ever since and have been fighting the urge to jerk off to these thoughts. I don't plan on acting on these thoughts but i just know id feel so relieved to be able to jerk while thinking about her feet but i dont know if thats acceptable. Please help me!!! Is it normal to masturbate to the thought of her feet???