FH's parents divorced 8 years ago. FFIL is still with the woman he left FMIL for, but they haven't married and I doubt they will.
Thing is, FH's mother is a little BSC and absolutely refuses to be around "that woman." FH doesn't want to invite FFIL's girlfriend, but a) they're a long-term social unit and b) FFIL and GF have treated me WAY better than FFMIL from the start since (unlike her) they're not crazy racists and (shocker) never once lost it over our mixed-race relationship.
What to do?