I'm in a similar situation. On our one month before the wedding day FI's mom, dad, and brother/best man all informed us that they wouldn't be attending. All with various complete BS excuses. I can promise you that I will not be getting over it any time in the near future. I just can't. I really have no desire to right now. My heart goes out to you! I Know first hand how truly hurtful it is.
I guess all you can do is learn how not to be from the situation...? I wish I had better advice, but I can tell you that I will be better over our situation for years to come.