I slapped my ex twice during our relationship. Once when he had me by the hair and another when he had me pinned to the wall by my throat. Both times the shock was enough for me to wiggle away, and put some sense in his head. By the logic a lot of people use he would have been justified in hitting me because technically I hit first.
If you're going my a completely strict definition of hit, in which only a quick strike counts, then yes. However, if we're using the "my *insert close loved one here* hits me" colloquial standard, I should think that holding you involuntarily by the hair or throat would count as the first move. What is meant by "you can hit back, regardless of gender" is "you can meet force with force in order to defend yourself, regardless of gender". Because by your same technicality, an abused man wouldn't be able to defend if his wife claws at him, throws things at him, chokes him, etc...because she didn't punch, kick, knee, elbow, slap, or headbutt.