i molested my sister in her sleep

a few months ago me and my sister used to sleep in a same room,when i couldn't sleep, i looked at her, she was asleep and i thought that her body is developing nicely, then i thought "what would sexual contact feel like", i repeated it a couple times at different days(less than 6 times), then came the time that i stopped acting like an idiot , ashamed, guilty and mad at myself for doing that sort of thing, i need help, i can't stand the thoughts that constantly haunt me, "you molested your sister" "you are impure" , it's draining what is left of my sanity, i'm 15 years old and my sister is 14,i used to be bullied, i live in a 3rd world country where even 8 year olds know about so much perverted things, where the environment is in bad condition, where i had lost my belief in a loving god, i think this played a part in my teenage stupidity, if anyone could ever help me overcome this guilt, please do so, i would appreciate it.