I'm going to ghost a friend group after bridesmaid selections.
Why would you want to ghost them after a selection?
I don't want to be their friend anymore.
That is something mean for you to do. You shouldn't ghost your friends. You may not be happy with the decisions that were made, but it isn't their fault and you shouldn't take it out on them.
Can't trust them with another wedding.
Fair enough, but you still shouldn't ghost them. If you don't want to be friends anymore, tell them yourself.