Do the card for the dog, AND do things for the house. You can buy easter chocolates and put them on the dining table with a happy easter sign... and tell her if anyone comes over they are welcome to them.
You will have to gauge this on your own for the most part. If you do'nt think she will handle the card and gift well then do it for the dog... I wouldn't do anythign to indicate you are just friends, she will take that as you having given up on your marriage... You've been consistently (mostly save for a few setbacks) sending messages you love your marriage and want to save it.. if you give her a card saying 'we're just friends' it will be mixed messages.
This is what your WIFE does...sends mixers... If YOu stay consistent it helps you out.
Again you can always get something for the HOUSE that's easter related...
