I'm sorry for the difficult time your family has had Sam. And I agree with others that separating may feel like it would make things easier. But in practical and emotional terms it is likely to make things much more difficult for you both and for your family.
From all that you post it sounds as though you and your W still have love for each other. I would encourage you to see this crisis as a 'breaking point' in that things have to change - but not at 'breaking point' (or end) of the marriage.
I would dig as deep as you can and be as honest with your W as you can about how you truly feel and what you truly want. I would also encourage you both to see a good marriage counsellor (Google Gottman) and receive some supportive input to help you get your marriage back on a better path. You may also want to consider IC for one or both of you to work on healing past painful experiences too.
Best of luck with whatever you decide Sam
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