Wow, if she just found this out about her father, she is probably expecting you to support her? Even if you have to be her sounding board, do it?! This is what a marriage is for, your support, and her support, you support each other!
You must have known how your future wife would behave from all of your dating, and even seeing how her family lived, right? You say she is conservative, does that mean no skirt above the knee? Keep knees firmly pressed together? That kind of conservative, or the political side?
Like I said, you had to of known her before you married her, so you should have known this is what you get? You can't cheat on her! Especially right now that she has found out her daddy might be dying? She needs you, she needs you now, more than any other time in her life! Be there for her, for her whole family if that is what it takes? Put your feelings of sex behind you for the time being. Your wife needs you to be strong for her right now!!!
Hey, sorry for the lecture! I hope you see where you need to place yourself? You know, at your wifes side? Hold her hand, squeeze it from time to time so she knows you still care? Sit down with her, and just hold her. Don't make any sexual moves on her, just let her know you are there for her.
Who knows, once daddy is out of the picture, your wife may loosen up in time? She may come to love you more because you were there for her? Just be prepared to take this to the end, and then some? Once she has grieved her loss, she may be very horny? Who knows?
Remember, this is about her at the moment. Time will tell, don't you think?