Father passed away, now his wife is liquidating everything

Location: Washington State

Brief backstory: my dad is a successful business owner. He has five children who were all grown when he met and married his current wife. She had made it clear on multiple occasions that she wanted his children out of the picture completely. She has never worked or contributed financially in any way.

Several years ago he began showing signs of dementia, so power of attorney was given jointly to dad’s wife and my eldest brother.

Then, dad’s wife had a different POA written up that named her as primary and my brother as secondary only if she was not available. She had a friend of hers notarize this. According to a caregiver who witnessed this, he had no idea what he was signing.

She then started transferring titles into exclusively her name. Cars, property, and other assets.
My father has recently passed away, and she is stating that there is no will. I don’t believe this to be true, as he kept one in his safe. She says she doesn’t know the combo but is hiring a locksmith to attempt to open it. A sheriff’s deputy has to be present for this to happen, because the safe has firearms in it. She’s not allowed to be in possession of firearms, so I’ve been told she is going to transfer them to HER BROTHER. Not any of his kids… her brother.
I should add that his assets have been frozen while this is in probate.
This is my father’s legacy, in the house I grew up in. I feel like she is doing whatever she can to squander everything he worked for. My siblings are crushed with the loss of our dad, and now his belongings are being given to someone we don’t even know. Everyone is saying this will be handled in probate but I’m worried that by making herself power of attorney, she could have had time to make it look like everything is hers.
Where do I even start with this?