How should I let a friend know that she's not included in my bridal party?

We haven't been close for years but she has only a few other friends and had an expectation that she would be included as a bridesmaid. She found out through one of the bridesmaids that we had already gone looking for dresses, and she said she was devastated because she wanted to come (although we had never talked about it!). We are having a super intimate wedding and only inviting our family and closest friends - everyone else seems to have picked up on it but I'm so worried that she'll be hurt when she finds out she's not invited to the wedding itself! Your advice is appreciated!