Lusting after my sister-in-law after an erotic dream

Hi, English is not my first language, and I'm on mobile, so any typographical errors are my fault. I'm also using a secondary account because most of my friends know my usual username.

For the background:

I'm a 33-year-old male, and my wife is 30 years old. We have been married for 11 years. We are both quite religious and belong to a revivalist movement inside the Evangelical Lutheran church. My wife has a younger sister who's around 26 years old. She left the church a couple of years ago. She and my wife are quite close.

I have quite a collection of kinks, but for this story, the relevant ones are ballbusting and humiliation. My wife is aware of most of them, and whilst she is mostly vanilla, I have been able to inspire her to do some things I specifically want.



Now to the actual story:

Two weeks ago, I was on a business trip some 1000 km away. The first night, I had a dream about my wife's younger sister. The dream started quite normally with a gathering of friends and relatives, but at some point, I ended up on an outdoor sofa with the mentioned sister-in-law. We were facing each other and relatively close. Sofa was facing the dirt road going past the house about 30 m from it.

At some point in the dream, the sister-in-law put her both hands inside my pants and started kneading my balls with just the right amount of force to make me horny as fuck and caressing my member. Just when I was about to cum we had to stop as we realized that her dad (my father-in-law) was walking along the road and watching us. The dream ended there, but I woke up the horniest that I have ever been, with my balls aching. I probably had blue balls.

Luckily the business trip lasted still two days and I had some time to calm down my horniness. It didn't help a bit that later that same day, my wife sent a picture of her hanging out with her sister and a couple of our friends. It gave me a boner and made me jealous for not seeing the sister. And to add to the insult we are secretly trying to get the sister to bond with one of those friends. She has already shown some signs of interest towards him.

Unfortunately, I was on a business trip with a male colleague, and we slept in a studio apartment, so I didn't have any chance to release myself. I flew back home two days after the dream.

I haven't said anything to my wife as she's a more jealous person than I am and would most probably get upset.

Ever since the dream, I have been tempted to tell my sister-in-law about the dream. (That'll include humiliation about having a ballbusting fetish.) I probably won't do it because I'm not that close with her, and I'm quite sure it would just upset her and make me look like a freak. Plus, there's a possibility of her telling my wife about it, and that'll upset my wife and probably narrow my chances of seeing the sister.

I have since jacked off numerous times thinking of her. My wife and I still have regular sex, but I cannot stop daydreaming of her sister kicking my balls and usually that leads to me wanking.

I'm not sure what to do or not to do. Maybe the best thing to do is to let things cool down and wear off with time. It doesn't help that I'm Aspie, and that makes me socially a bit awkward.

Do you have any thoughts or advice on the situation?