I usually call mine "the x" or just by his name. However, I kinda like "the guy formerly known as my husband"! Too bad there's not an acronym that encompasses "weak narcissistic hypocritical adulterous priesthood candidate."
As for her--sometimes she's known as "the witch" because she is, actually, or "Wicca Woman." I'm having difficulty calling her GF; to me, that would belong to someone who came along after the marriage ended. Someone who knowingly and willingly initiated adultery with a man who has a child, contributed hugely to destroying a family and continues to do damage to my D13, isn't adequately described by such a benign term.
M60 H52 D20 M14 yrs OW-old gf from 1986 bomb-5/18/08 H filed for D-9/10/08 D final 4/24/09 xH remarried (not OW) 2012