I am so sorry for your loss. Your pain is obvious in your post. Your heart will heal in time. I am not saying you will ever be the same because you won't be, but you will heal. Beating yourself up because you didn't see or know is not the answer. You loved her with everything you had. It was something in her that went awry not you. You need to give yourself a chance to heal.
I haven't been on this site long but from what I have seen this is a loving supportive community. Everyone here is kind and they understand your pain and your loss. I am glad you are here and hope you find a little peace.