how to tell a friend she won't be a bridesmaid?

I have a friend who asked me to be in her wedding in November, even though we haven't hung out as much in the last few years just due to being busy with other things in life. During the planning process and on the wedding day she made various comments about how she would "do this all for us one day too" so she definitely thinks that she will for sure be asked to be a bridesmaid in my wedding. My fiancé was one of her husbands groomsmen, and he is going to ask her husband to be one of his. I have a lot of friends that I've known for years that I feel much closer to, and I don't know how to tell her she won't be in my wedding.. do I have to ask her to be in mine?