I think I have fear in 'doing nothing', because it feels like I'm not reacting or doing nothing when I should be doing something?!?!?! But it sounds like radio silence is my best bet at the moment.
No. You aent doing nothing. You are making a CHOICE to do nothing. Thats far more powerful than being a spectator. You are backing off and giving her the space that she is asking for. Yes, you should be radio silent unless theres something logistical that needs to be discussed. "Im confirming that you are taking the kids on XXX day" or "D is feeling sick - I gave her some tylenol, but we may need to take her to the doctor". Beyond that, what is there you need to discuss at the moment? You say that you are worried that she will slip farther away -- how much farther is there?
As for GAL, what are your thoughts on you being in charge of the kids every night? At least where I am, custody is determined based on overnights, so I would say technically, you already have full custody. There are TONS of ways to GAL even with kids - I know 25yearsmlc has made a huge list - volunteer at the kids school, volunteer to help coach one of their teams, look for workshops at the library during the day, do work on the house, look through your community bulletins, join a gaming group, and so on. You need to find something you are interested and pursue it. It will certainly be more difficult if you are the full-time parent. So make GAL a priority during the day while the kids are at school.
Like I said earlier - if you arent going to try to have full custody, it doesnt seem very fair for W to only have to parent when its convenient for her and you are there to pick up the slack all of the other time....