first of all, its not whether your hubby wants you to go that matters. Its your sister In law AND mother in law, do THEY want you to go.
you see, as all of us know, reunion dinner is a time to enjoy each family members' company... but if the sight of YOU makes them upset, or the sight of THEM makes you upset, then I would rather not go.
Ask your hubby to check with them. See what's their response. If their reply is, "aiyo, its so long ago ... we have forgotten about that issue already..." Then, please go.
if their reply is, "up to her . She feel like coming, come. if she dont't, then dont't." Then you should know what you should do...
its their response that will determine your decision....isn't it? *wink*