Ok so yeah ex-bf, it's kinda complicated right now. Not gonna reveal our ages just in case because I know he has a reddit account but we are both in college. Anyway, so after sex he asked me to hand something to him but called me his sister's name instead. I found it so weird and as I look back on all the things in the past, it just all kind of adds up. I have a personality of giving everyone the benefit of the doubt so I thought his excuse of him having his sister usually hand him things was valid. After that though, I was observing him on my peripheral vision and noticed he was being very fidgety and he was looking at me back and forth to try to look at my reaction. While I was at his place, I just pretended that it was nothing because I was shocked and I was unsure of how to confront him about it.

For context, I don't have a good relationship with my siblings so I was very new/not used to how he treats his sister generally because they seem quite close. Sometimes how he acts with/about his sister puts me off in a way that just really is not something I'm used to seeing. I just shrugged all those instances off because it really could be just me not being used to that kind of relationship. Also, I won't expound but something sexual happened between them in the past when they were kids (I do not know the full context of whatever actually happened because he only stated this in connection to telling me a story of something traumatizing that happened to him too, basically he said he did not know that what someone else did to him was not okay and did it to his sister thinking that they were only playing around). I'm not sure if it really was just because of a habit or if he has a thing for his sister or maybe it could be because of this trauma thing. Honestly do not know what to think and I am very conflicted on what to do.