I want to fuck my sister-in-law

Good morning, the day I come with this story and fantasy that I have been having for a long time now but my desire has increased recently. My sister-in-law is a very pretty girl (over 18), beautiful eyes, lovely lips, big booty, small breasts. I know her from a long time ago through the relationship I have with my girlfriend (her sister), and I always thought she was an interesting girl. I never knew any of her boyfriends so I think she's still new to all this. The times I went to visit my girlfriend at her house and stay with her, her sister was always there, never left, a quiet girl who doesn't go out to parties or anything like that, but her lovely face and beautiful eyes deceive people into ignoring how spoiled she is; capricious and very crazy. Every time I saw those attitudes of hers, I thought that girl just needs someone to get her but I never thought I would be one of the ones who most wanted to give it to her. With time, she started taking more confidence in being at my house and began to stop wearing a bra, which I obviously noticed because even though her breasts were small, you could see her nipples showing through the long blouses she always wore, that's how my desire for her started to grow little by little. But the straw that broke the camel's back was a song where everything that could go well, went wrong. It was an afternoon when I almost had to leave for home but before I had to go to the bathroom, so I headed there, which just happened to be next to my sister-in-law's room, I was walking normally without any morbid thoughts towards anything, but when I saw that her door was open and turned inside, I saw her, it were some of the most pleasant and morbid seconds of my life, she was putting on a long blouse and wasn't wearing anything else, she was standing profile so I had the pleasure of seeing her small breasts and enormous and delicious butt. She didn't notice my presence because it was too fast, between the bathroom and I quickly took off my cock and started masturbating thinking about what I had witnessed, I was so impacted that I didn't even notice I hadn't locked the door. Then this same one began to open and when it opened fully, it was my sister-in-law entering without knowing I was here, she stayed frozen looking at me and my cock, couldn't help but look at me and then back at my cock, I froze too with my cock in hand until she said 'sorry sorry I didn't see you were busy'. That day I didn't see her again, but something curious happened, when I got home I kept masturbating thinking about what had happened, thinking about her, a few hours later I received an Instagram request and it was from my sister-in-law. I immediately followed her and in no time she accepted me, seeing her photos made me masturbate again even though most were just of her face they helped me think about her, and to make matters worse I saw that she posted a story and noted that she posted it on 'close friends' there I realized that indeed the photo was for me, the photo said 'never leave anything unfinished' when I read that and saw the photo I confirmed that it was directed at me after seeing that I couldn't come in her house when she entered. Time passed and I kept going to my girlfriend's house and her sister no longer wore only a blouse with nothing underneath, she usually wore a short skirt and a blouse with a bra underneath, I got hard every time I saw her and remembered everything, when I saw her she would blush and avoid looking at me but I know that in the end she wants my cock and of course I'm willing to give it to her. I can't imagine anything else except giving her a good one to take away the bad and crazy way she is, when I have sex with my girlfriend obviously I think about her sister and get hotter. But until I give her my cock there's nothing more to tell about it in a post. I'll keep you updated on everything that can happen pass. Many thanks if you're reading this and enjoyed this experience I had. If you want to talk more or see her in another picture, I'd be delighted to introduce her so that more people can see her and have the same feeling I do of wanting to give it hard, send me a message with all confidence.