BF might be going to jail

So my bf likes to troll people/pick fights on a website. Usually it's people that are racist or whatever. For whatever reason he decided to troll a post that a drug dealer made about selling drugs. He joked via private chat he wanted too buy a gallon of cocaine and dumb stuff. Well the "drug dealer" was an undercover cop. They were able to figure out that it was him they're talking to and reached out to him in person when I wasn't around. Arrested him, read his rights etc. Questioned him, etc. They released him after questioning. But recently he got a letter in the mail for a pre trial (forgot the actual term),

I collected the mail and noticed it was from department of justice I thought it was weird as its usually court related and I wasn't expecting him to go to court so I asked him (at this time I didn't open the mail as it's his and I'm not that type) he said it was nothing but I pointed out it was from the department of justice and was heading to grab the envelope to show the logo on the mail, but he quickly took it and tossed it across the room and insisted it was nothing. I was annoyed so

I just left it be in 10ish minutes he told me what happened (what I mentioned in 1st paragraph) after him crying and stuff we opened envelope and I noticed his arrest, / questioning happened Jan 7th so he kept everything a secret for over a month. According to the paper he could get 0-90 days in jail and 0-1000 dollar fine. I'm not necessarily mad that this happened I'm more mad and feeling betrayed that he hid such a major event from me for so long.