I read your long post about needing to let W go and go through her own journey while you are fighting your own internal doubts about wanting the M to work or not. As Steady indicated to you, it is what IT IS. You have no control over what W does or does not do; however, you are in complete control of yourself and your destiny. Make the most of it while W is running around with the OM and his ragtag gang.
Let's take a realistic look at where things stand:
1) W is still with OM 2) OM is starting school soon 3) They are living with two other adults in a house (not exactly comfortable existence) 4) Their finances are apparently strained
Possibilities down the road:
1) OM starts school in few weeks 2) School work will be the added pressure to OM and W 3) OM will be exposed to the "elements" at school that will divert his attention away from W 4) Fights will ensue between OM and W over this 5) Stress and haggard looks will begin to show up in W's face & body language
This is when you will need to put your best DBing foot forward, bud! Time is a changin'...be quiet and watch. You will need to present a stark contrast to OM when interacting with the W: Mature, experienced, steady, humorous (hint, hint), cool, calm and collected. Do not forget the odd new shirt, new shoes now and then to unsettle W with your changes.
How is the house makeover coming along? Still putting on your own personal stamp to the house with YOUR stuff?
Time is a changin'...be quiet and watch. You will need to present a stark contrast to OM when interacting with the W: Mature, experienced, steady, humorous (hint, hint), cool, calm and collected. Do not forget the odd new shirt, new shoes now and then to unsettle W with your changes. 
