A Little Secret with my brother in law

My brother-in-law Brian and I have a secret that we have never told anyone. It happened quite a few times more than six years ago. I was twelve at the time and he is four years older than me. My parents own a cabin in the mountains and since I can remember we always had a full house on weekends with relitives and friends. It only had two bedrooms so most of us kids would sleep on the floor in the living room on top of our sleeping bags. The first time I remember this happening, Brian was sleeping between me and my sister who is today his wife. I had twisted my ankle that day and was having a hard time sleeping from the pain. I was crying a little and it was really late and Brian asked me if I was ok. He started to rub my back, I thought to comfort me, and moved closer to me. It felt good and I could feel his hand go under my nightgown but didn't think much of it. He massaged me for a long time and he even massaged my rear under my panties. I didn't protest or try to stop him and really didn't think anything sexual about it. It felt wonderful and I shortly fell asleep. A few weekends later we were back at the cabin and when we went to bed Brian was beside me again. This time I was asleep and not even sure what time it was. I could feel his hands on my back and and he whispered to me to relax and started to massage me. I admit I enjoyed it and let him pull my nightgown all the way up as he did. I think I was still half asleep but liked what he was doing to me. When he pushed my panties down and rubbed my rear I still didn't object and let him fondle me. After a long while he gently pulled me over on my back and started to rub my legs and chest. I was just starting to develop and what breasts I did have were very small. I knew then I shouldn't let him do that but I was so relaxed and it felt so good I let him continue. His hand came between my legs a few times and he did touch my vagina but only slightly. The next time it happened was a couple weeks later and I was sound asleep again when I felt him rubbing my back. This time however he not only pulled up my nightgown but I allowed him to take my panties off completely. I just let him do whatever he wanted and he was rubibing my whole body after awhile. He got me to turn over on my back and started by rubbing the inside of my thighs and touching my vagina. I didn't completely realize it at the time but now I know the feeling I got was arousal. He soon started to masturbate me and again I never objected and had my first orgasm. The rest of that summer I would purposly make sure I put my bedroll next to him knowing full well what would happen. He would always start the same way and eventually get me face up on my back. Thats when he would start inside my thighs with one hand and rub my breasts with the other. I became more aware of getting aroused and aside from getting wet , my nipples would get hard. He did get more agressive eack time but I never once told him to stop and would orgasm a few times . I don't know how I justified it in my own mind but liked it so much it didn't matter. I found myself looking forward to it each time.The last time we did it he got me to touch him and he guided my hand to his penis and I ended up masturbating him as he was doing it to me. I think that was the first time I realized it was a really bad thing that was happening. The next day I knew Brian also felt bad about it. After that I was really ashamed of myself and it was difficult to be around him. I never told anyone what we did and Brian seemed to avoid seeing me and when I did see him it was awkward and humiliating. A few months had gone by and one night when he was waiting for my sister we were alone. He turned to me and just started telling me how sorry he was for doing all that stuff in the summer. I told him I was sorry too and we promised each other we would never tell anyone, especially my sister. Over the next couple years we were more comfortable around each other and it never happened again. On a few occasions when we were alone we did talk about it and each time he would again apoligize and tell me how sorry he was. I know he did take advantage of me but I did let him do it and did enjoy every time he did. I started masturbating back then and still do sometimes today. I think about it sometimes even though it happened so long ago. I actually don't regret it but I truly beleive Brian does. He married my sister seven months ago and I would never dare tell her what happened at the cabin and I'm sure Brian never will.