Am I crazy to assume that, if I tell one person but don’t specify any particular privacy settings, they would leave it to me to decide when I disclose it to others?

I guess I should get specific here. I was officially diagnosed a couple of weeks ago, as having autism spectrum disorder level 1. I have so far only told my mom, who I live with, and my best friend, who I suspect is also autistic. Today, I overheard my mom talking loudly on a video call to my brother and his wife, catching up and sharing their latest news. Apparently her latest news included the fact that I have been diagnosed with ASD. I hadn’t yet decided how to go about having that conversation with my brother, and now I’m pretty upset that I don’t get to make that decision. While I’m venting, she also mentioned that I’ve been less conversational lately, which she attributes to my diagnosis and to me no longer wanting to make the effort necessary to talk to neurotypical people (in reality, my chronic fatigue has been playing up lately, which always leaves me with less energy for conversation - she knows my chronic fatigue has been playing up lately, but apparently thinks I’m just choosing not to bother).

Am I crazy to think she was way out of line to share my diagnosis with someone without running it by me?

I’m also not sure how to move forward with this information in any way without it seeming like I was eavesdropping - which I wasn’t intentionally doing, she was in the living room / kitchen area, I was heading down there to make myself a cup of tea (which I do every night at that time, in the room that she was talking in) and froze halfway down the hallway when I heard her sharing my confidential information. I didn’t know how to deal with the situation so I just stood there for a bit and then returned to my room without making the cup of tea. If she had directly told me that she had told my brother about my diagnosis, or that she was bothered by me being less conversational, it would give me an opportunity to provide input on these matters, but as it is I don’t feel comfortable raising the subject, or noticeably increasing my level of masking (to accomodate her apparent discomfort with me not doing so), without the eavesdropping issue potentially becoming part of the conversation and complicating matters.

I’m also bothered because I have a tradition of once a year going to stay with my best friend for a while, and typically stop off with my brother for a few days when I pass through his city. Last year unexpected travel complications left me burnt out, so when I made the bookings a couple of months back for this year’s trip, I made it as simple as possible, including skipping the stay with my brother. I haven’t yet told him, and now I’m worried that he’s going to take it as me no longer socializing with neurotypical family members (even though the arrangement was made before my diagnosis). The whole thing is complicated and no longer under my control because my mother decided to share my diagnosis and her thoughts about my behavior behind my back.

Anyway, I guess I’m venting, and looking for input on whether this is as infuriating as it seems, and maybe advice on how to approach the situation.