Don't "address the issue" of leaving expensive things in high-traffic areas. She already knows that. She's probably as mad at herself as she is at you (but she's taking it out on you) ... and you're going overboard to placate her by buying replacement earrings. Her things are ultimately her responsibility, and if she didn't want them lost she wouldn't have left little losable things in a high-traffic area.
The big issue is it sounds like she wants to parent you and treat you like a child, and then you give her fodder by missing the mark on things like packing the kids' bag ... Regardless, you kick it back to your "ADD" but really a lot of it is just being accountable for a human error and being allowed to make human errors. She feels powerful and in control when she can put you in the "he's just another child I have to care for" mold and anything that goes wrong can stay your fault. It sounds like she's looking for things to treat you with disrespect about, and you help her find them. But now wouldn't be the time to address that issue. That issue is best dealt with over time by manning up on the accountability front and standing up to her infantilizing you.
Either way ... "ADD" ... is a really bad excuse. If it's a justified excuse you need to get the shit dealt with to make it not an excuse any more.
For now, stand up for yourself and acknowledge that everyone is stressed with the holidays. Help her look for the earring by all means, but don't let her ascribe more blame to you for it missing than you deserve. If the kids' bag wasn't packed all the way and you said you would take care of it, you should apologize for that, but if it was only partly packed because you didn't know what all needed to be packed, you need to let her know that too.
If you stand up to your wife now, she'll know you'll also stand up for her later.