My Dad gifted his money to his grandchildren before passing away. He wrote gifting statements instead of a Will. Is this legal?

My father passed away, I was his POA. He was a difficult man and rest of family wanted nothing with him, they did not like him, when nobody was there for him just me, he felt abandoned and told me you better not give any of my money to these people, I advised him , since you don't have a will or anything, I don't really know what happen, so he said im gifting all money to grandchildren and you, so we wrote gifting statements and he signed them, is this legal what we did? Also for some reason he did not want his money in his account because of social security pension, he thought the government was going to take it, he made me put it in another account, the only half brother is asking me questions of missing money, do I have to tell him that dad gifted me money since he was not there when he died, he told me don't bother me, I have a sick feeling in my stomach. Family is mad, these are his wishes.