I do think living together must be difficult in these circumstances. When I read the threads of others who cohabit at times like this, I do feel that is the hardest situation.
I always work on the basis of - decide and do. If you decide (for your own best interests and those of your kids) that it is time to separate, go ahead and facilitate this.
If you remain committed to saving the marriage, and want to continue being in the same house, do that.
I don't think the 'who should this come from' is a useful question. Maybe you feel it 'should' come from your W as she initiated wanting to end the M.
But we can all wait around for others to do what they 'should' do - or we can get on and do for ourselves.
JMHO of course and hope this helps :-)
T 13 M 7 Me 48 H 46 SS 15 BD 7.14 PA D final 5.16 (H filed)
We receive & we lose, and must try to achieve gratitude & embrace with whole hearts whatever of life that remains after the losses - Dubus