It must be so hard. Hang in there for your S and yourself.
Clearly W does have feelings for you and regret, but she has to decide what to do about it. You need to keep getting yourself in a good place no matter what.
I'd probably help here move if I thought I could keep it together probably because I'd want to demonstrate being there for someone you care about, even if you know they are doing the wrong thing (moving out), is important to me. Its ok for her to see that you're sad she's leaving - you are. Its important she also she's that you're strong enough to survive without her, and are true to your values like helping others.
