help my brother

me & my brother were watching stories on serial killers, started with ted bundy & after that the suggestions from youtube kept rolling and we kept watching, one thing was common in all the next stories: homosexual men. And as we watched the aura around my brother kept getting darker (info: he's in a relationship with his bestfriend for the last few months and it took them some 4-5 years to get to that point cus my brother though he was straight), and after we were done he went into this nail biting-sweating like a pig mode and kept questioning his beliefs cus he somehow derived that homosexuals aren't sane so if he's a homosexual relationship he isn't sane either and he has to get rid of this 'pervertness' otherwise he may end up doing shit like this too . He hasn't slept for days and is avoiding his partner and today I saw cut marks on his arm. I tried to reason with him saying there are plenty straight serial killers too so these clips don't prove a point but he just won't listen. I don't want him to hurt himself or his partner anymore

these are few of the stories we watched:
https://www.youtube.com/watch?v=FnutYM4sgPA
https://www.youtube.com/watch?v=rbrL40XHlPQ
https://www.youtube.com/watch?v=SRYZORutlq8
https://www.youtube.com/watch?v=rbrL40XHlPQ
https://www.youtube.com/watch?v=t3PA37erNYw