Wait, did LW just straight up accuse her youngest son of lying about the oldest? "The family knows he didn't commit this crime" - would your youngest son agree with that assessment? Because he's part of your family, and judging from this letter I doubt he's retracted his accusations, so....

Yeah, Oldest should not have been tried as an adult, much less placed in adult prison. Those things are bad, no matter what crime the minor in question is accused of committing.

But we can separate this fact from the fact that the criminal justice system believes Oldest did something extremely serious, based on the evidence and also his own brother's accusation, an accusation that he is still making.

The boys aren't asking anyone to take sides, but we all are feeling jerked back and forth

But you are taking sides. You can't help but take sides. And you've taken Oldest's side against Youngest.

Like, I can't even handle the advice portion of this letter until LW actually admits that this is what she's doing. She's taking sides!

What can we, as a family, do to bring our boys back together?

Some things can't be mended. Those two know who did what to whom, both in the past and in the present.