I.A. Latham, the mysterious cut character from early Half-Life 2 development. Originally designed by Ted Backman and first appearing in HL2's artbook Raising the Bar.
So I got into L4D real hard and looked up the character wikis and voice lines and something something, the Witch crying reminds Nick of his ex-wife and the wedding area "brings back bad memories", something something, "it's not easy to get blood out of a wedding dress" "last time I saw this many crying women was at my wedding" and uh, what the fuckity fuck happened at his wedding????