Go to 2 or 3 lawyers for consults. Ask around for recommendations. Talk to a mediator who is also a lawyer to determine if you would rather go that route. I would skip the self file or one of those insta-files like legal zoom. If you want this to happen as fast as she does then it will. However while you can't stop D you can pull the breaks and slow it down. Get all the info you can, be on top of the D process.
Following Steve's thought process when you talk about D with wife let her know what your lawyer advises. That will wake her up a bit. It probably won't stop anything, but at least she knows you aren't just going to roll over.
H(37) W(35) D8, D5, S3 T20, M13 BD 8/31/18 EA Discovered 9/13/18 Mediation 10/3/18 W files for D 10/12/18 W moves out 11/10/18 EA confirmed 12/25/18 D Final 1/10/19