When is a wife eligible to receive half of husbands SS?

I am 72 and have been receiving SS since I was 62. My husband is 74 and has been receiving SS since he was 62, A friend insists that I am eligable for my SS that is $605 a month, plus half of my husbands which is $850 a month. And that my husbands would stay the same and my would increase my $425. That would be nice but I think his information is faulty. Can you settle this dispute.