Nanjo doesn't even know about the time he tried to slit his wrist and he got called out by Nanjo manipulating him when he was drunk out of his mind and is embarrassed the day after, which shows he wouldn't have done it sober. He already knows Nanjo won't cave just because he's crying because Nanjo had no problem saying he didn't want to see him anymore in chapter 34 when Mokyeon was crying. Mokyeon has many faults and did many things wrong but I fully believe he's expressing his real feelings in chap 39, not trying to argue with you or anything tho, these are just my two cents.

them crocodile tears ain't moving shit bro