Was i wrong for having with her?

ok so im 18 an my friednds sister is 16 an she has been like a sister to me sense i was 8 an she was 6 years old i mean i have know this girl for so long an always protected her an never ever thought about her in a ual way i mean i have looked at her an was like dang she is pretty but i was just the look as like u woulf look at ur own sister an be like oh she is pretty time to lock her up so no guys will ever hurt her....thats all i have ever looked at this girl like she was always like a little sister too me....but ill tell u the story....ok so i was at my friends house for the weekend about a week ago ya last weekend i was at his house for saturday an sunday.... an i was tired cause of a basketball game that saturday....so i wanted to take a nap so he just went to the store when i was a sleep an he texted me saying he would be back at about 10:30 an it was about 7:30 an i was like ok so i hooked up my XBOX an started playing xbox live an his sister got home an was like hey brother an i was like hey whats up an she sat by me an we were just talking an before i new it she was running her finngers down my chest an ABS an i was like hmm she never did this before an for some reason i didnt think anything of it an was like oh well an i was wearing a plain black shirt an she was like take off ur shirt please an did the little puppy dogg face to me an i was like why an she said cause u have an amazing body an i was like ok i guess an so i did.... an she like kissed my chest an i was like wow an she wasl like what an i sat down....oh ya an this girl is a model well had the body she has the body that all guys want there girls to have but ya she was like a sister to me.....but anways we were sitting there an she was tocuhing my abs an she was just doing it allslow an i had my PJ's on so i had loose pants on lol.... an she put her hands down my pants an than started giving me a hand job a N started kissing me an i tried to stop but for some reason i could it almost felt right to me an before i new it we were in her room naked on her bed doing it an we did it for about 2hrs at this time i wasnt even thinking about anything but how it felt an how good it was....an so we got done an she went made something to eat an i played some games again an started to think an thought wow i messed up nopooooo what have i done!!!! my friend is going to kill me an he ended up not even caring he said he new it was going to happen one day anyways.... so please someone tell me do u think this is wrong what i did or not? cause i mean npow that it happen i think of her a little more an she wrote me today an was like she wants to try dating but i think its only cause i took get V card idk i dont know if its wrong or not