I’m not a lawyer or police, this is my educated guess: If he had called police, they would have talked to both of you to get the details. He’d say you pushed, you’d say you leaned. If they thought it a volatile domestic situation, they’d probably remove one of you and take you to the police station and ‘book’ you (but it’s also to protect you both from further abuse). Then you’d get a lawyer who would plead that it was nothing illegal and charges would be dropped. Meanwhile, this would cost you money, stress, possibly more harm in custody, and worsen your whole domestic abuse situation.