Phew stubborn... wish I had some good advice for you. I am to the point like you that I will not make my Hs choices for him. And I will not make his choices any easier. So... we can speak our piece and then have to leave it at that. I think you continue doing what you are. If W is busy on the computer at night... get out of the house. Go to the library or whatever... doesn't have to be out to a bar or club, but your S doesn't know that.
I am sorry for this sitch you are in. I feel so similarly to you. And I wish I had good answers. Best thing I can do is tell you to let her go and you might have to get really mad to do that. In my head, I'm letting my H go. It's his call right now. I will not try to convince him to stay or anything. but I will stand up for my kids and myself. Ugg... i know this isn't being very helpful. You are doing a lot of things wonderfully and I understand how you are feeling. You need to just take back some of the power here and decide that enough is enough. I'm not saying push your S to leave... but decide that you matter more than how you are being treated and stop caring about what S does. Easier said than done, I know.. but I'm going thru this myself and for the first time in a long time, I feel power and peace w. my sitch. Good luck stubborn!