Wendy, It's a tough pill to swallow when they bring you what you need to file for divorce w/a happy smile on their faces. What you need to do now is start working out the legalities of your finances. One of the things that they will request from the both of you is a listing of all financial expenses, etc. So, if you have time, you might want to start on that.
As for the ow, your sister needs to stop engaging her. The ow could be dangerous and and it doesn't take much to send someone this nutty over the edge. Your sister thinks that she is helping you, but she isn't...she's making the situation worse in the long run. You also need to ask her not to share any information about the ow w/you. You have to keep your mind focused on what is at hand and not have any distractions now.
As for your h, he will find out that the grass isn't greener over on the other side of the fence in due time. I'm so sorry he's moving forward on this.
Wendy, please take care of yourself.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.