What is this?! What is he hiding from me?!

Me and my boyfriend are both 19 but he's about to be 20. He lives with his mom and I love with my roommate. He hasn't been talking to me as much as he usually does. He said a lot has been going on. When I was over his house yesterday we were playing video games and his mom asked to speak to him and pointed to mail. He came back and put the letter in his dresser. She needed to talk to him again so I went into the dresser and found this! He's obviously hasn't been telling me something.

Edit: My problem is the domestic violence part. I'm his girlfriend so who's committing the domestic violence/deadly weapon assault

Edit 2: I'm asking who supposedly committed DV against him. I'm his girlfriend. I know I didn't committ DV again him so who did it? Is he cheating and she found out about me, hit him and that's what this is?