D.P.
First and foremost, keep the two events separate. Don't mention to the friend requesting addresses ANYTHING about the rift between you & former friend. That's just not appropriate. Give her the information she has requested from you in a non-partial way.
As for your shower, a few thoughts:
•Life is measured by milestones: births, deaths, wedding, etc. I would NOT exclude this "former" friend from this milestone in your life because you are not on good terms right now but feel you "will eventually work it out".
•In life, it's always better to take the high road.
•If you invite her, the ball will be in her court, which is a good place for the ball to be, right? She has the option of declining--you already know that might be a possibility. If she does, then deal with that and know that it speaks volumes about her character and your friendship's importance to her.
•I think it's always better (spiritually) to do the kind thing, don't you?