"My kids need to see me, and I will do what it takes to make that happen, within my rights of course."

Have you picked them up and kept them for a few days yet, nothing is stopping you. Your wife is apparently capable of doing it, nothing stops her, you are capable also, let her know that you're picking up the kids and just do it. Pussyfooting around with emails & texts will not get the job done.

Call her, "wife, I'm picking up the kids today after school, they will be with me today, tomorrow and Saturday, I'll drop them off Sunday at noon."