(((HUGS))) I know how frightening and troubling this is. My daughter half-heartedly attempted suicide 5 times in a 2 year period. I say half-heartedly because what she did wouldn't have killed her, but it got her the attention she wanted. A couple of weeks worth of anti-depressants isn't likely to kill someone. I've found out that it's a lot harder to kill oneself with pills than most people think.
You ask how this incident should affect your detachment. If it were me, it wouldn't change my detachment in any way. If you allow her stunt to bring you back, she will have gotten what she wants and anytime you try pulling away, she knows she can just take a bunch of pills and you'll give in.
Your second question pertains to the possibility of "blood on your hands." If your wife were to actually succeed in suicide, you would have no blood on your hands. What she did was directly related to HER OWN bad choices, of which this was another. No one can fault you for taking care of yourself and your daughter (or am I confusing you with another member?). Please don't let her manipulate you into trying to "take care of her." You can't. Chances are good that she won't try anything like that again, but then again, she might. My daughter tried multiple times until I finally said ENOUGH and made her find another place to live; something she never thought I would ever do, and quite frankly, neither did I.
I know how scary it is when they pull a stunt like that, but do not allow her to benefit from it in any way.