Angelo

I think "another brother under the club" may refer to his being around people on the occasion the song is about that were in a motorcycle club (he being under them; a non-member simply attending a party). He probably slept with the wife of a connected individual while at a party held at the fellow's house. He (likely purposefully) in the rarities version makes his voice seem to quiver at the line "I would still be true to you" after mentioning his having had a shotgun pulled on him. "There's no way out" is just referring to a bedroom with one door in which is a man with a shotgun and expressed intent to use it. "There's a halo over me" is referring to his opinion being that the ordeal was a manifestation of extreme good fortune (or a guardian angel perhaps). However I believe a member of a genre-similar band that was around at the same time is also named Angelo.