I had a sort of similar situation, sort of... Julie and I had been friends since we were 4 years old. We kept in touch even though we lived in diffrent countries for a while. We came from 2 totally diffrent backgrounds...
She came to New Orleans to visit me for Mardi Gras and we had her bachloret party while she was here. She decided after I hosted a long "party" weekend and bought my bridesmaid dress and all that she did not want me in her wedding anymore because she did not like the guy that I was dating at the time (even thought we had been together for 5 years at the time and she had met him a million times before). If I broke up with him I could be in her wedding.
I did not break up with him so she kicked me out of her wedding. She told me that I had changed and she did not like the new me.
What is funny is that I did not like her soon to be husband, he was not good enough for her. She was always worried about what he would think and she always seemed unhappy when he was around. I never told her that. She was not the same Julie anymore either....
That was over 5 years ago. I am still hurt by all of that. She never once apologized. She called me recently, out of the blue, she is still married and has 3 kids. She wants me to come visit her, but to tell you honestly, I don't want to see her. It's amazing that something as happy as a wedding can change friends.
I think you did the right thing by sending her an email. I don't have the guts to do that right now. I bet that your friend did want to call you/email you and tell you about the relationship but maybe she was worried about your opinion or maybe she was worried about the change of relationship too. It is also easy to get swept into the worlwind of a new relationship. Sometimes, friends that you would normaly call to gush about the new relationship get put on the back burner for a while because you are just to wrapped up in the new man in your life...
Good luck to you and your friend. Just remember, this too will pass!