I don't know of any online support groups for family members but you (or your spouse) can always vent on here! I am the mom of IBD children and this forum has been a godsend to me. I can ask lots of questions, discuss my concerns and fears, and find the support I need. Nobody judges. Even though the family does not have this terrible disease, it doesn't mean that they aren't hurting too.
I do know that local CCFA units often have support meetings for families. I have never been because this forum has been what I need but you may want to look into it.