Copy cat bridesmaid

So I'm am looking for advice from people who are maybe experiencing the same issue. I have been planning my wedding for almost 2 years little by little and putting in a ton of effort for every little detail. I have 3 bridesmaid dresses that all match but give my bridesmaid choices for the sleeves because some what different ones then others. I totally do not want to be a bridezilla however I have a bridesmaid who is getting married also. After we have had our date set and our venue locked down and paid for since the beginning of the year, they picked the weekend before ours just 2 months ago and she is now copying the details I have in my wedding. She also asked me to be in her wedding. About a month ago she sent me a dress she wanted for her bridesmaid dresses. And I told her I would order it the following month. Her reply was that they were discounting the dress and it needed to be ordered within the week. Not only did that give me 1 week to drop $200 but the dress only had 2 sizes and not one anywhere close to what I am. I put my foot down and said I was not doing that as it is not fair and I already was planning my fiance bday party amd a baby shower that month. The last straw was when she sent me a picture of a dress she picked... and it is the same exact dress that I picked 6 months ago for my bridesmaids. I replied with oh you are having the same dress as the one I'm having? And she came back with I'm not trying to copy you I will change it. No worries. I'm not copying. And it was not a problem. And then the following day came back and said this is the dress I'm having and just because I picked it in 5 seconds doesnt mean I'm copying you. I just like that dress. . . She also has been talking badly about her sister in law for the last 6 months because all she does is copy her. And when I confronted her about it she keeps saying I'm not copying you. I'm not copying you. And is now acting like it's no big deal amd because she said she is not copying me but picked the same exact bridesmaid dresses that I picked 6 month ago and doesnt get "what the big deal is?" And then said you said no one picked that dress sk I dont get what the deal is. When in fact my matron of honor and future sister in law has already purchased and recieved this exact dress.
I asked 2 friends for opinions because I can be rude and overreact, but they both told me she is being ridiculous. But am i being crazy? And i in the wrong for being upset about it?
I really want to tell her that I dont want to be apart of the drama she is creating and not be apart of her wedding. I dont need to stress myself out about this or be upset when I have put so much time and effort into my own wedding over a wedding that is being thrown together in a short amount of time.