I think im in love with my brother in law.?

a few weeks ago, we had a little fling. . well more of him had a fling to be honest because i know it was wrong to betray my sister... but i kinda liked it :S i feel awful for liking it... i did not go onto him or nothing he was just mainly nibbling and biting at my neck... and.. kind of moved me down to missionary and just started nibbling more and he wanted to do more and i did stop him each time it got to touchy... and also i stopped him because it was wrong and everything!! hear me out i dont think i stopped him well enough though because i guess i was in shock i just couldnt belive this was happening? but it did lead to one thing to another.. unfortunately. and ever since i can't really.. stop thinking about it? what is this? why do i think about it? i feel awful but i can't help myself.. i just get this.. weird feeling in my heart and i cant stop thinking of that night.. guys and gals i'm not a slag but how can you control your feelings its impossible. hope ya'll understand