P, I don't post here often but please, please stop and think about what you are doing. From an outsiders perspective it looks like you are making an effort to scare her away forever.
Just that first sentence "I need to talk to you". If I was her, being in the mindset she is in, I would have stopped reading right there. Then you go on to demand that she explains her feelings to you? And the next sentence is "I'm not going to pressure you" which is what you just did.
And you don't file to send a "strong message". You file because you are done with her and her behaviour and you have given it enough time to think about what's best for you. Your marriage has been dead for a while. I get the feeling you are holding on to some of Sandi's rules like never give up and therefore ignoring most other rules. In her mind, the marriage is over and she has made that very clear to you.
Me: 38 Stbxw: 35 No kids Mini bd: February 6, 2019 ONS confirmed Sept 7, 2019 Told her to move out: September 8, 2019 W moved out: September 28, 2019 Divorce filed by me: September 23, 2019