I'm Rin, the one who typeset this manhua. Well, I wanna explain it about the time written on the phone, so you guys will not blame us (it's not a mistake, just we leave it like that). That is the original part from the artist, we didn't change that part, cause i think you all will know that "am" written there means "AM", well, it's kinda weird for us, but we forgot to clean that page and leave it as the original part
(=・ω・=)
Here's my opinion about "why the seme chooses to hurts his father's son over the father himself" is when someone hurts the one you dearly love, it'll make you suffer even more (that's my own speculation tho). I think the seme thinks that Qing Yu is one of the dearest person to his father, that's why he chooses to takes revenge to Qing Yu (to makes his father more sufferer)