Hang in there. Yes, this might be the toughest thing you'll have to go through, but the ending might be a very happy one, so stay positive.
I would show your W that you care by taking off time for work and help her out with the kids, especially if she complained about you not contributing enough in the past. This would be a 180.
About the gift, I would buy a separate one so she feels that she's missing out on getting the gift for your D together.
