Is it bad wedding etiquette not to invite the stepmom, to honor the real mom?

I've been a friend to the bride for 18yrs. 2 wks. before the wedding I was told by my partner that his daughter didn't want me there and her excuse was honoring her biological mother in this way. The Bride & Groom paid for everything themselves so nobody could have a say in what happeded. Now the wedding is over and my partner has told me that his daughter still wants me in her life but she has yet to talk to me herself. I'm very upset that after 18yrs of being called the other mom, that someone could do this to me. I don't know how to get over this so that we can all be one big happy family again. Or should I just chalk it up as a loss and get on with my life.