Bride - level four rudeness - may need to drop old friend from childhood to level of "used to know her when we were both children - don't know her very well NOW". Whether to choose the cold shoulder for a while or go immediately to the cut direct is up to the letter writer. But the bride has clearly shown that she is a baboon with a very blue backside... She has also proved that her logical reasoning skills never got beyond age two or so. "My party + where's my present?" instead of "Friend has no job + she has no money coming in - she has no spare money for travel, bridal party clothes, presents, and the like. So her presence and support is her gift to me."
Letter writer - level one rudeness (at most, by comparison to Bride's) - friend might be a bit rude, but if you've caught rude fleas from a baboon with a blue backside, scratching doesn't make you a baboon, too. It means rude fleas bit you and you itch. Her level of rudeness is so much less in comparison that it is noticeable but most people would probably excuse her as long as she didn't push the bride off a cliff, just the porch!
Bridezillas need to be hit with a BIG clue by four, sometimes a clue by eight. The bigger the Bridezilla - the bigger the clue needed.