i wasnt meant to use my bros phone

ok so like last week my bro left his phone on the couch and i just started scrolling through it. at first it was cool, looking at all of his apps and stuff. but then i found this group chat he’s in with some of his friends talking about me and my sister. turns out they were making fun of how we always fight over the remote and stuff. and i’m like yeah i do that but also why is everyone else laughing? i was pretty mad so i started typing a message to tell him off. then i remembered he blocks all messages from unrecognized numbers and i couldn’t even send it without him knowing it was me. plus i realized how messed up it would be if he found out i looked at his phone. still trying to figure out if it’s better to just forget about the whole thing or talk to him but i’m not sure what to say.