I'm so sorry for you loss and probably the PTSD along with grief you are experiencing now. Please know, you probably couldn't have stopped her even if she did tell you. I have read this to be true by professionals so many times, the regrets & thinking you could have stopped a loved one from suicide. My friend's brother committed suicide 1.5 yrs ago & her relationship was similar. She blamed herself, thinking "if only I would have asked him this... or if only I would have given more support... " As you know, on the list goes. I pray you are receiving help for all that you've been through & send good thoughts you way. I'm so sorry for your loss.