I fully understand what would lead the parents to do this to themselves, their own breaking points.
But it is indeed a monsterous act to murder the kids. They weren't terminally ill and physically in agony with no help from doctors, right?
I am sure the boys valued their lives and didn't want to die. So for the parents to take their lives, because how dare anyone else have the chance to take over after their own suicides and care for their boys and love them.... Nope.
Murdering special needs kids is not something we can start to excuse.