Last night we had a ridiculous 45 min argument with my FMIL over the guest list. Of her 6 siblings that live here in town, there is 1 that she says we cannot invite. This woman and her husband have never been anything but kind to me and my FI. Also, their son is the cousin that my FI is closest to. I said that we would invite them no matter what FI agrees and that began the argument, the majority of which I didn't understand since it wasn't in English. FI later told me that FMIL threatened that the rest of the family would boycott or that there will be fighting, both verbal and possibly physical, if we invite them and everyone shows up. Please tell me I'm doing the right thing. By the month after the wedding, they may all be friends again and I'll look like the ss who didn't invite them.