Hi everyone

So, I'm looking for a bit of advice on how to respond to an unhappy sister.
I've already chosen and asked my 3 best friends to be my attendants, I have no regrets to this desicion, it's the best one I can make.
I love my family and I think they are all wonderful. My 3 sisters are 9 to 19 years older then me, and while we have great laughs and tears together, they are not my best friends. We didn't grow up together and rarely talk except at family functions.
I got a call from one of them yesterday, saying how I should choose them as my attendants. OMG! What a horrible and awkward phone call that was! She is a very emotional person. Half way through her bullying tactics and sobbing, she says she only brought this up to tell me that she's OK with my decision. Yeah, right....I decided to pretend to believe her, so that we could just forget about it. Today I received this email...sorry it's so long. Maybe I'm now guilty of reading in to things, but it seems like she's still trying to guilt me about my decision, I don't think she's actually being supportive here.
Is it so wrong to want my closest people to me despite them not being my sisters?
It irks me a bit that she's making it seem that it's bad that I'm closer to girls outside my family.
I want to respond to her, letting her know that I'm upset that she feels so entitled and has put me in this very awkward position. Who tells the bride that they should be the bridesmaid?! But, I don't want to make this into a big family drama either. What should I say?
Thanks everyone

PS did I mention that her one and only attendant was not one of our sisters? Things that make you go 'hmmmm'
My Dearest Sister,
This is in regards to our phone conversation the other day about your wedding. I felt sad for you after I thought about the whole thing. To me, I wouldn’t expect this to be as hard of a decision or a pressured one at that. I certainly didn’t want to do that... although I think I did. No one in your family, including me, wants to put the pressure on you, that is not what we are here to do... in fact... you are lucky... you have a family that has been pretty supportive throughout your whole life.
We are very lucky to have a family like we do... so many families are not nearly as close as we are... even if you don’t think we are that close... Just think about it for a moment... Our parents have tried to keep our family close... We get together for holidays, birthdays, camping, vacations... etc. We are there for each other through the good and bad times and always will. We share all our news and get excited for one another... we cry with one another... we laugh at one another.
Families love each other unconditionally, even when we don’t agree with each other’s decisions. They have fond thoughts of one another as well as fights that happen. But the thing is we forgive one another because we simply love each other. We respect the others decisions even though we don’t understand or agree with them. Families only wish the best for one another and have each others back.
I think you are closer to your family than you realize. And for those who are not as lucky as you wish they could have a family like you have.
I know you love us too but to think that your relationship with anyone else would be more important than the relationship with your family is sad. I really feel sad that you think this. You may not talk to your family as much as your friends but I have to tell you... talking to each other is not the only thing that is important... it is more than that.
We all are not perfect and we love each other anyways. We have made our mistakes yet we always make amends because we care about one another.
Family will be there through the thick and thin and the best of times... Forever....
I am not writing this because of the wedding... It really has nothing to do with it.... I am writing this because I felt sad that you don’t think you have a relationship with your family that is stronger than the one with your friends. I only wish you one day can see it differently.
I haven’t been as close to some of the family but... I have to say... I always keep them closer to my heart than my friends... because they are my family...
Your wedding is your day... It is a celebration of the beginning of your own family as well as an extension of the one you already have. We are all happy for you both... You will have all the love and support from your family. I hope you know that.
You have always had a special place in my heart and always will.
Love you... very very much,
Your Sister,