I'm guessing at 5 weeks in, she has no idea what she's feeling and it may change minute to minute. With time she will settle in to some realization. I think the reality of their choices hits them like a brick in the face, when it comes down to it.
As far as the birthday text, follow your gut. I would send it, but to me birthdays are extremely important (everyone's, not just mine). I would go with your instincts so you have zero regrets later.
Me: 39 H: 45 Second marriage for both H left 12/2013 M:4 T:5.5