How to get rid of bridesmaids?

I am getting married in May and have 5 friends that are supposed to be in my bridal party. Two of those girls were my college roommates and so called best friends over the past few years. I have always noticed that they didn’t connect with me as much as they did with each other but had hoped that would change with time. Things such as calling each other best friends but not me, planning birthday parties for themselves, and even getting the apartment that we all spoke about getting together without me. We grew apart in this past summer since they lived together and I went back home but quickly became close once school started back in August. Things were going great and I felt like they really valued our friendships so I asked them to be bridesmaids which they accepted. I realized within weeks later that I made a mistake and should not have asked them. One of the girls decided to plan an elopement four days before my wedding and said she was taking the other girl with her. When I asked if she could move her elopement date she refused and said that I have no say in her relationship. Now I know she does not owe me to have every day before my wedding free but my bachelorette party was supposed to be during the days she had planned for her elopement. One of my bridesmaids is flying in from out of state so I am not able to move the bachelorette dates and find it very hurtful that she would even think of planning her elopement so close to my wedding. She is having a large wedding in a year so I did not see the issue with moving the elopement day a little further from my wedding date since she is going to be getting a large celebration still. I was also not invited to this elopement which was hurtful because I thought we were all best friends. Over the past few weeks I have noticed that they have lied about what they were doing and would hang out without me and do the plans that we all had made. I have also heard about them speaking poorly of me to others. I have tried so hard over the past few years to make these friendships work but just feel like they will never care as much as I do. I am devastated to have to kick them out of the wedding but am quite frankly miserable with them being in it. This was supposed to be an exciting time in my life and I feel like they only care about what benefits themselves. I am never one to seek to be the center of attention but was excited to get to be celebrated with my close friends and now do not feel that excitement because of those two bridesmaids. I am needing some advice about how to let them know I am wanting them to step down from their roles. I know that they will not take it well no matter how it is worded but I still want to try to be as polite as possible. Any time I have ever brought up an issue in our friendships they don’t understand my side of things and I end up making peace with them but I would like to stand my ground on this decision and do what is best for me this time. It hurts really bad to have to do this because I know they will no longer be friends with me but I have to do this for myself. Please give any advice on what to say to them!