Tad, The "telling you" about picking up your son is her way of controlling the situation. Also, they are so absorbed w/themselves, that they don't stop to consider that the world doesn't revolve them and that you may have plans. If you and your son have plans, then you need to let her know. She needs to learn boundaries and life does go on.
I had to chuckle about cringing when the phone rings. I still do that today and more so if my xh emails me, even after all of this time. I know that when I hear from him, he wants something...never fails.
It takes time to learn to trust again, but it will come. Tad, just give yourself time, don't rush the process.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.