<human>: Long story short - my entire life my brother has been emotionally and occasionally physically abusive. You can read more of the details on this post from a few days ago:

My best friend, who is from my college town, came to visit, having heard this all from me but never having been to my house before. The entire time she's been here, my brother has been overly sweet, kind, not screaming or berating me per usual. I also think the fact that his girlfriend is here has something to do with it. 

So she keeps saying "Oh he seems nice, not that bad, etc." and I'm feeling very betrayed. This guy has given me emotional scars, my parents refuse to see his dark side and now my best friend does to. I'm very hurt by her reaction and I don't feel like I can trust her anymore because she's buying into his BS. What do I do? I don't want to lose my friend over my douche of a brother but my feelings are very conflicted.

Can you give me the gist of the text in a nutshell?
<bot>: Best friend visiting my home for the first time, buys into my brother's nice guy act even though he's an abusive asshole, I'm feeling betrayed and I don't know what to do.