There's nothing wrong with saying, "things are a little hectic right now" or, "now is not a good time to talk". She should not expect you to be available to talk all the time. You have your family that is your main priority and you need to decide when you'd like to talk with her. If it's never, that's fine. If it's the next day after the kids leave for school, tell her. If that's the case, suggest that it's best to talk when the kids are in school. Maybe try setting the timer and when it goes off, tell her that your timer is going off, which means that your phone break is over (hey, I'm a timer person, work with me

) and that you'll talk with her another time. Or set up a time to meet for coffee. Don't make it your house or you might never get rid of her.