I understand the shock you are feeling - the official stamp on her actions that signals her moving forward - but it's really what she has been saying all along, and she probably got advise to apply for CS so she wouldn't be depending on contact with you or handouts. She wants to be independent, so this is a part of it - she doesn't want to rely on your gifts.
At some point, you have to get from "I can't believe this is happening to me!" to "Okay, this is happening, now what do I do about it." Your hopes and expectations have to go out the window. That is what is called disengaging.
You were going to see a L yesterday? How did that go?
M 16 yrs, WH62, P54 3 adult blended kids EA 11/13, BD1 6/14 PA fall 14, BD2 2/15 Piecing 2015, BD3 12/15 Separated 4/16 WH moved OW in 5/16 Divorced 6/15/17