It drives you crazy because you allow it. You are both addicted to the drama. If you weren’t you wouldn’t answer her calls. Your kids are roughly the same age as mine and I haven’t spoke to my ex on the phone since November. You know why because there is no need for it. My kids have phones and anything logistically we text. I certainly would never let my ex talk to me the way your ex talks to you.
It’s possible that these calls could be to see if you if you finally grew a pair and are ready to stand up to her, but you routinely fail the test. I just hope your kids can overcome this toxic behavior.