Responses
Yes he is stupid and coward (not being sarcastic) and that's the reason this whole manga/novel exists.
It took me 2 reads to understand that he is only 16 yrs old, a teenager, who did not have a happy childhood, just to realize that his so called “mother” actually swapping him and not to mention knowing that the other one living so good and pampered & liked by the whole family, not knowing if he will receive the same love from his biological family if he reveals the truth when his own "foster family" didn't liked him.
Lastly our main character wasn't all so perfect and nice as angels type of person, he had his flaws.
If I was the mc (not happening ofcourse) I will go over and tell them the truth rather than seeing your supposed family supporting other, because in the first place, all of lele is his in the first place, all those privileged should his in the first place. He should not overthink for what if, he should just go over and tell them the truth hence I called him, stupid. If ever he tell them the truth and they accept him or not, he will move on himself, so that he will not imagine what if. He is stupid and a coward