LuL: Yes, I heard about this “minhag” too
About your quandary (why would you be speaking to a friend’s husband?) I think him referring to his wife a “my wife” sets her apart from you, in a subtle way. We wish to remain an Am Kadosh, and we take steps necessary to be ?????? ?????? in any way. This is one way, setting a “boundary” through speech. So even when you must speak to a man, his wife is not “Soshie” but “My Wife”. That sets them apart. So much more so when he’s speaking about her (c”v no lashon hara) to another man.
How you address another man? I guess your method works. I know that sometimes I’m addressed as third person when in the presence of a bunch of girls/women, as a sign of tznius. It rubs me so bad, to me it’s so untznius. (“Would Little Froggie please come over”) Just say “you” – “could you come here?” So plain and simple. Nothing to it!!!