Should I feel guilty for what I have done..?

Guys. Thanks for being there. When one thing settles down a new one arises. My mind has got over with the suicide stuff and just when you feel things are falling in place a new stuff comes up. Well, I would like to tell what happened to me today. I am working as a research assistant lately. I am assisting a senior girl in her thesis and we successfully completed it and today was the last day. Being her little brother I like playing with her and I consider her as my elder sister. This girl happens to wear clothes which might be a bit revealing. Also she happens to play with me a lot and today while I was in my car and was supposed to drop her to the railway station she kissed me on my lips! Guys look I know this might not seem a very small thing, but she is my sister and this brief kiss has created a negative feeling in me. I feel as if I did something wrong! I then told her I don't get it and would you mind doing it again. This is the mistake I made. And my sister again kissed me! Both of these kisses lasted for about 5-10 seconds. I was shivering. For 23 years of my life I never kissed any girl. And now it happens to be with a girl who ain't my biological sister but who considers me as her little brother. I am still confused as to whether I did the right thing or wrong. I am away from P all this while since 2 weeks. However while she played with me (playing here refers to biting my hand, tickling me and pulling my cheeks), I did feel some stuff and I used to unconsciously wet my pants. This is happening since last 2-3 weeks wherein everytime she touches or plays I feel aroused and also when I keep my hands around her waist and rub her stomach. Of course I am in senses to know that I should not dwelve ahead and that she is my sister. But is this a normal thing to experience? Did I do something wrong. While I haven't been doing 'M' much lately, I can't get it with O as it comes naturally? I kissed my elder sister! This makes me feel sad and weird. As if I have forgotten my principles. She said she won't tell her boyfriend about it as I am her brother. But I don't know?I don't want to be guilty for what I have done, but at the same time I feel I forgot the values my parents taught me, that I am turning into a bad guy. I don't intend to be there...! Please guys I know, for some, this may sound weird and lame as to this is just a kiss, but still it is something which I never experienced ever until now where the first kiss was something which she gave and the second one was one which I asked for as I was confused having the first one. Help me get over with this guys..!

 

I appreciate your help man, but you see, we have a trust among us. To be honest I am from India and here a sister and brother have a sacred Bond as we have. Like we don't indulge in stuff that seems to ruin this. Hence, I said it's a thing which many will find as small, but from what I have been brought up with it is looked upon as a bad sign in my country.. That's why the guilt

 

Appreciate your support man. Thanks. But I myself don't want to indulge in this. It happened a lot spontaneously and also she will be married to her boyfriend in year. So, as I said we consider ourselves as siblings though we ain't biologically related and being my first kiss, kind of makes me all more conscious. Back home here in India, this doesn't work out well. Still appreciate your help.