Just let her know your there when or if she wants to talk. Never say anything bad about the ex, as sometimes they get back together ( though it never seems to last long), try and keep her busy, shopping, going out for lunch and encourage her to go out and see her friends, this is the most important as if she spent a lot of time with the ex she will be feeling very lonely. I've got 2 daughters, 6 and counting broken hearts. Doesn't get an easier, as we don't like to see them upset and knowing we can't make it better.