That is horrible
I am sorry that your family is like that to you! It is good that you realize this is how they are and you can't change that, but don't let it get you down. I've noticed that the people that try to knock you down are just projecting their own insecurities on you.
I am sure you will look beautiful in your wedding dress! If I was you I would not let them come to the ceremony. If they cannot be happy for your why would you want them their on the most joyous day of your life? Unfortunately you cannot pick family, but you obviously don't need them if they bring this pain to your life.