/nsfw/ - xxx

Just like it sounds, I been with my bf for a while but just recently met his brother. They are carbon copy of each other, chinese, 6'2, tanned, somewhat muscular as they used to do a lot of sports; almost twins if it wasn't for their age difference.
My bf is very open about sex, we have had multiple talks about crazy things we've done in the past even fantasies. I never really been interested in a threesome or being with another guy outside of my couple, but this time it's different and gotta admit, I feel a little bit guilty.

The three of us spent some days together to get to know each other. Went out for dinner, went to the beach, all kind of things. His brother was not really good at visual contact but conversation was very easy with him, so I could tell he was not uncomfortable. After a while I notice that he was always discreetly eyeing me up and down. The day at the beach was not the exception, things scalated very quickly, they were teaching me how to swim, they had some distance in between them so I could swim back and forth. In a moment his brother held me close to him to stay afloat. Right there I felt it, hard againts my leg. I couldn't even hide my surprise and he quickly apologized. I went to my bf to tell him about that weird interaction but little did I know he saw everything and hugged me by the waist and started rubbing me under the water. "You liked that, right? I'm sure he liked too".
I WAS IN SHOCK 💀💀💀💀💀 I never had a situation like that happened to me. My bf just kissed me and went outside the water.
The rest of the day both of them acted like nothing happened! I sunbathe the whole day while they're playing paddle and volleyball. Both came from time to time to check on me.
The next day i was looking for my bikini and the bottom part was gonne the whole morning. After a while i found it where i left it to dry the day before… 💀
He left a few days ago, and I don't know if we'll meet again in a while. Not a single word about the beach interaction was said before he left, neither about my bikini; which I told my bf about and he replied with "I wasn't me" while giving me a mischievous look (mind you, this man stole a bikini bottom too when he was a teenager, so it wasn't that strange to him).

I feel like they're were waiting for me to take the first step. I just didn't know how or if it was correct. I'll be a lie if I said that thinking about both of them on top of me didn't make my head spin.

I'm also concerned about incest, if they have a threesome does it count??? My bf told me they used to kiss and touch each other when they're kids/preteens. I used to do the same with my (f)cousin, but once we reached a certain age we stopped and never thought about her again.

Any advice? Should I do it?

(This is not a fanfic,(as some people thought on reddit) pls i really need help