Sorry to hear of your 16 year struggle.
From what I know about aneurysms, the slap to the head would not likely be a cause. The congenital weakness would need to be there first. I have an 'minor out-pouching' as described by the radiologist but it has never been a problem despite my many bumps to the head. Imaging for my concussion caused symptoms found this abnormality.
More likely a high blood pressure event, possibly brought on by stress or excitement caused the weakness to blow.
Either way, not more slaps to the head.
My best to you.