I think Lexie is right--your wife may be feeling just as disconnected.
The "breathing room" of legal separation may give you both the space
to work out your feelings--and for her to be able to cope with the roller coaster
of early sobriety without having to deal with family issues which may be beyond her right now.
Sometimes relationships aren't for a lifetime--that doesn't mean failure
if lessons are learned, growth happens, and parting is compassionate.
I strongly agree that raising a child in an unhappy home is far worse than
a "child-first" divorce.