At 27 years old a professor put his hand on my shoulder and I recoiled.
It looks like PTSD.
You might want to check out some of the symptoms of Post Traumatic Stress Disorder and also a guy I think his name is Lindsay who wrote on PTSD variants he was suggesting to revise the DSM IV.
Best you can do is pull up the vignettes that are your memory for the event, if they are nasty, get treatment and then go from there.
A buddy of mine does yoga and it seems to work for him. There are also techniques for progressive relaxation.
I think you'll be coping with an exaggerated startle response for a long time. I haven't been able to rid myself of it personally. But other guys may have better experiences.
IROLL here's what you do: Get a compressed air horn for about $30 - they're full of compressed gas, and when you pull the trigger, it will make yer brother go through the roof. Sometimes reversing the trauma can be, well, if not healing, maybe satisfying.
- when he's taking a dump, lol use the air horn.
- when he's on the couch sleeping after too much alcohol, put a lit cigarette in his hand let it burn for a minute or two, then scream "Brother wake up you're smoking in bed what're you trying to do burn the house down?"