pardon me for well intentioned bluntness man,
but it seems to me you're making too much of a meal of stressing yourself out over future "what ifs" and "might she"'s.

Its obvious to everyone that the only priority is here and now putting as much safe distance between your kid
and her junkie mother,
for as far and long as necessary until the woman either starts to pull herself back together
and kicks the dealer outa her life;

[or he, and maybe she, gets arrested, or dies]

..and while you face up to the realities of being a good solid effective single parent
in the eyes of state welfare authorities,
who may always retain the option of stepping in
to releive you of responsibility for your kid,
if you ever come to their attention and concern as being a weak incapable father.

Its a much more simple crisis than the over-wraught
soap opera you seem to be writing yourself into for the next 16 years or more.

take care man.

and I so hope and wish this actually is a cynical fiction
to stir up mudcatters reactions,
and no guy is realy having to endure the dismal life you describe here.