I empathize with you. I wrote in with a situation that had some things in common with yours.
Before death, one of my parents said, with no prompting and in front of a witness (an attorney) that I would receive a significant amount of money. Following the death, I got nothing, my other parent got it all.
Very little, if any of the estate would have been in probate. Most of the estate was non-testementary- equities, insurance, pension, etc. Two properties were jointly owned, everything was jointly owned. Surviving parent sold those properties and bought two others in a different state. Transferred all accounts that I know of.
I suspect undue influence and diminished capacity, but suspect is all it is, no way in the world I can prove it. I live 3000 miles from the county where the death occurred, so without hiring a lawyer there, I don't even have any access to the will. I certainly don't have funds for that.
On this board, the two posters who replied to you, adjuster jack and Ford, also kindly responded to me.
In my opinion just because it is legal does not mean it is ethical, but my opinion, like what I got is worth zero.