No, it's not the same. When they were younger it would have been easier for them to process than it is now knowing they've been lied to. In addition to finding out their Dad killed people by driving drunk they have the additional baggage of knowing they've been lied to for years. When I was 8, my favorite uncle died due to a drunk driver. He wasn't killed on impact, he suffered. Seeing the inside of the van covered in blood shocked me. It was hard to process. So, my mom took me aside and explained what happened. She told me how he died, what happened to the other people, and let me know that while his death was hard he was reached and treated quickly, so he wasn't in any pain at the end. That helped me process it. Asking questions and getting honest, tactful, answers. If I found all of it out years later and that my parents had been lying to me I'd have been furious. Furious and heartbroken.

It would have ripped that wound wide open and plunged me back into the sorrow I felt when he died. Instead of having years to process, grieve, and move on now they're being faced with all of those old feelings plus the devastation of the lie. And OP is now put in this position, by her mother, of whether or not or even HOW to tell her brother.

You're all judging her, but this isn't fucking fair to her. My parents have always had an open policy of honesty when it comes to family deaths. And I've lost so many people. I've become really good at processing my grief and moving forward. Her mom did her a disservice by lying. Period.