Xia Jing knows that his son doesn't want to hear any explanations from him right now. In the depths of everyone's heart, if you can explain your past mistakes now, it just proves you're guilty and trying to cover up the errors you made. Everyone would think that way, let alone his son. Even if no one else knows what his son is thinking deep down, as a mother, she will always understand the thoughts within his heart. His ways of thinking are different from others.
However, his son still sees him as his mother deep down. If it weren't so, he wouldn't keep forgiving the many mistakes he made. To his son, he's nothing short of a monstrous villain, yet he's forgiven without hesitation. This proves that as a mother, she will always be a part of him. If he could truly gain her forgiveness, then what regrets would he have in this lifetime?