1) Cannot stress enough the importance of speaking to your L first before you start doing things financially. You may put yourself in a position where your W still has rights to the money you're setting aside, EVEN IF there are certain "agreements" in place - depending on your state. Make sure you are covered legally so that anything you start building up won't tip the scales and put you in a worse place should D have to happen.
2) Regarding your W and all the things she is asking / expecting and how you are analyzing them - I think you are thinking WAY too much about her. I am not saying I don't do this too, by the way, but in your last post it was really super obvious that you are still letting her behavior (which you KNOW is not logical) bother you.
It is definitely harder for you since you are still living together. That was one of the major factors in my sitch that I couldn't handle, and it only lasted a few weeks in my case before I had to tell H to go. HOWEVER, you do have to weigh, again, not only the legal aspect of moving out but ALSO the reality that you will not have as many opportunities to interact with your W and show her your 180s, etc.
I totally get your conflicted feelings on this because it will absolutely help you to detach, but you just have to be prepared for what may happen either way (continued cake-eating while you're together, or her potentially seeing you moving out as even more of an opportunity to get deeper involved with OM). I somewhat regret asking my H to move out for that reason (I feel it expedited him and OW getting serious...but maybe that's just the illusion I had, I don't know).
Also, I'm not the best at "prescribing" actions based on DBing principles since my sitch was too far gone before I got here, but if there's anything you could do to make sure you are not only validating your feelings, but also expressing what YOU would need (setting the boundary), that may be good. I totally understand that you have likely done that before without result, and without her active willingness to work on the M with you, it does sound like cake-eating.
Definitely stay calm and don't get angry and vindictive or "punishing" toward her.
H:39 W:30 M:4 T:9
05/2018: H says "ILYBNILWY", BD 07/2018: Discovered A, confronted 09/2018: PA + other details emerge; H moved out 12/2018: I filed 03/2019: Divorce finalized