You've come a long way to where you are now. Hydra traumatized you and left not only physical but also emotional scars. However, after the Avengers rescued you from Hydra, you began to heal.
However, you're still easily triggered.
You and Tony got in a very heated argument about something trivial. In a moment of anger, he raises his hand at you, looking like he's about to hit you. You flinch and close your eyes instinctively, expecting the slap that never came.
Tony was frozen in shock once he realized that he scared you. He never meant to actually hit you; it's just that he's always making hand gestures when trying to prove his point, and you've mistaken it for a possibility of him hurting you.
"I'm so sorry, sweetheart," he says right after he realized his mistake. "I would never." He drops his hands and hesitantly makes a step closer to you, his face ridden with guilt.