FHs sister not happy

So me and my FH are due to get married in just a few months. We have invited those closest to us and mostly family we see or who keep in contact. My FH invited his sister and the children who live with her. This was stated when we handed out our save the dates a year ago and this wasn’t a problem then. We received her invite back a week or so ago stating she wouldn’t be coming because her other children and grandchildren (who we haven’t seen or even heard off in over a year despite trying to keep on contact) haven’t been invited. She didn’t just stop at the no thank you. She started hurling abuse at my fiancée because of this and telling him he’s no longer family and family means nothing to him. Are we in the wrong for not inviting them? I personally want to give her my opinion but the OH won’t let me. I just feel bad that he’s essentially lost a sister because she can’t be happy for him and allow him to have his day how he wants it. We’re holding a small wedding and limited the ammount we invited.