Johnny didn't push her into talking more. She was just breaking the surface of her feelings at this point. He'd gotten her to at least open up about it. That was a good start. They could work on the rest of it as time went.
He wrapped his arm around her, pulling her close and holding onto her tightly. The hot tears soaked through his shirt and he instantly felt bad for all of this. While he was aware that Mary needed to at least go through this once, he would have gladly turned back time and never brought it up. Let Jo do it, or Dean. Let Rob. Let anybody but him be the cause of her tears.
It was done, though. So all he could do was hold her up so she wouldn't fall too far.