We TOTALLY missed sending an invite to FI's aunt, who he lived with for parts of his life and I haven't had the chance to meet yet since she lives across the country. She got the STD, so she knew it was coming. But I still feel so badly. Luckily I caught the oversight when I was playing with the seating chart today. I was looking for her name assuming it was in there and it wasn't... which prompted the investigation.
FMIL thinks she is already making arrangments to come for the wedding, so getting the invite a couple weeks late is OK. I guess we are still within 6 weeks. That part makes me feel a little better.
I'm going to start breathing now...