I thought Cliff Richard's song "Devil Woman" would be perfect for this ocassion:
"I've had nothing but bad luck
Since the day I saw the cat at my door
So I came here to you, sweet lady
Answering your mystical call
Crystal ball on the table
Showing the future, the past
Same cat with them evil eyes
And I knew it was a spell she'd cast.
She's just a devil woman
With evil on her mind
Beware the devil woman
She's gonna get you
She's just a devil woman
With evil on her mind
Beware the devil woman
She's gonna get you from behind."
Seriously, whatever works to keep you from calling the ex is good, even if slightly irrational!