Yep, Taekyung didn't know anything why Heejae left or abandoned him. Because the incident was filed confidential by Heejae's hyung. And that's the reason why his hatred towards Heejae turned to revenge.
And no one else know about Taekyung and Heejae's relationship when they were in high school.
Even Taekyung couldn't believe that Heejae become a dumb person. o.o
And about the "Heejae forgave him too fast" thing, you can see Heejae's inner thoughts cursing at Taekyung while listening at him. That's just how Heejae have become. Just like when two kids fight but after a few minutes or a few hours, they're playing happily again. o.o
Haejee didn’t care about his family’s business anyway and it’s not like it collapsed
i kind of hate Taekyung cause he ruined Heejae's family business even tho Heegyum might have deserved to be exposed for his evil ways. I also hate that he manipulated Heejae when he doesn't even know the full story!!!!!! Heejae forgave him too fast and wasn't even thinking that Taekyung was trying to ruin him and get revenge!!! I thought Heejae lost some of his IQ to below average but i didn't know he had an IQ of 0!!