Sarah, At first my W was in a rush to get D. I was able to hold that off for a year but in the end, she found some excuse for going forward. The time that it takes for them to get through this is a lot longer than we could ever realize. For most of that year I gave my W NOTHING but space, left her alone, even supported her so she could go away for work or to visit her father (who I knew was actively trying to get her to file!). She slept on the couch, went out with her friends (sometimes not coming home as she had too much to drink) while I watched the kids and I never said a word about any of it. I let her do what she wanted, when she wanted, no expectations. Didn't make a bit of difference. She was bound and determined to leave and if I didn't do anything to make her unhappy, she made things up that she "knew" I was doing or thinking!
I'm not saying you should make it easy for him. If he wants to get a D, let him do the work, find a lawyer, file, etc. When he brings it up just say that you don't think D is the answer and leave it at that.
In the meantime do the DBing. GAL, do some 180's that you can see might change the dynamic. Work on discovering what YOU want for YOU. I spent too much time hoping that since she hadn't left and stopped talking about D but only "separation" that things may be getting better. In less than a week, once her father came to town, she went from "separation" to filing without saying a word to me about the change! Now that she has filed, she hasn't been following up on it or even talking about the details. Let him spin. You need to be the best person you can and I think you are doing well on that front.
