My brother lives with my family (me, DH, 2 small children). He is neurodivergent and sometimes finds life a challenge. But usually he is an extremely kind, selfless person.
Earlier this year we had an au pair who was romantically interested in him (at some point she drunkenly told him that she was falling in love with him). I made it pretty clear to him that it was not appropriate for him to be pursuing a romantic relationship with her; she's (early-mid-20s) over 10 years younger than him, the power imbalance obviously was huge, and frankly I didn't want to have to deal with the complications that could arise from a relationship turning sour between two people living in my house. They both told me they weren't interested in a relationship with each other (my brother was just coming out of a long and, in my opinion, horrible relationship).
They were often going out together or staying up late drinking together; I was happy for her that she had fun things to do but to be perfectly honest the late nights sometimes led to her being tired and grumpy when she was supposed to be working (and my brother's drinking has been a concern for a long time). What I didn't know was that when they were drunk they were - I guess the best term would be 'fooling around' (I have zero interest in learning the details; I know they weren't sleeping together). What I also didn't know was that at some point this did turn sour from the au pair's point of view, and that my brother didn't notice. (My best guess having spoken to her a bit is that she realised he also wasn't interested in a relationship with her, and given their continuing physical contact she felt a bit used and hurt - despite her saying the same about him. That's just my conjecture though.)
This all came to a head a month or so ago when they got home at 2am, my brother woke us up being loud and drunk, and the next morning we found out that one of his friends (I'm going to call him Jack) had slept on the au pair's floor. We had a serious conversation with my brother about his drinking, and spelled out that he had a choice to make between his current lifestyle and continuing to live in our home. AFTER having that conversation with him, the au pair (this is starting to feel a bit depersonalising; let's call her Sophie) said she needed to talk to us. She told us that the reason 'Jack' had slept on her floor is because he'd witnessed my brother's behaviour towards 'Sophie' and been horrified, and felt that she might need some security. Sophie told us that for some time she'd been avoiding my brother when he was drunk, because he was a bit handsy. She didn't tell us exactly what had been happening, and the conversation was clearly extremely difficult for her so I wasn't pressing her for details. The next day I spoke to Jack and he described what my brother had done as 'sort of tonguing her neck'. The important point here really is that an independent witness saw the behaviour, clearly understood that it wasn't consensual, and was appalled by it (Jack said many times that if he hadn't witnessed this himself he never would have believed my brother would have done something like this).
My husband and I were obviously completely horrified. This is a young woman we feel responsible for who didn't feel safe in her own living space because of predatory behaviour. My mum came down on the train and spent the evening talking to my brother, and he enrolled in an alcoholics programme. Sophie said she wasn't 'bothered' about it, but a week or so later she left giving us 3 days notice. There were, unrelated, issues with Sophie: we had noticed that things she said didn't always match up to her behaviour, and the day she gave us notice the manager of a local community centre had just contacted me and told me Sophie wasn't taking care of our toddler at all when they visited it together, to the point where he was at risk of seriously hurting himself (another parent on the school run has since told me he observed concerning behaviour by her around our children). But this is getting really long so I guess I'd better cut to my real issue, which is that I feel some of my family are massively minimising what my brother did. I spoke to my other brother about it recently and when I described it as sexual assault, he said "a lot of the rhetoric used regarding that incident has been completely over the top" and that Sophie "had given [my brother] reason on previous occasions to believe that she was consenting". I still can't believe that a member of my own family thinks like this about sexual assault - like, what the fuck is the relevance of her consenting on a previous occasion?
So: AIBU? Is this an extremely serious event which everyone in the family should be taking seriously? Or an understandable drunken mistake? For the record, the 'drunken octopus-hands' brother, as far as I know, is taking it seriously. It's the other one who doesn't seem to be.