My husband and I are having a serious argument here.
Okay, so Fredo made a deal with Johnny Ola that wound up being a hit on his brother, Michael, head of the Corleone family. Though Fredo was mislead and didn't know they would attempt to kill Michael, he did go against The Family.
Michael kicked Fredo out of the family, but said nothing would happen to him as long as their mother was alive (he did not say this to Fredo). At their mother's funeral, their sister begged Michael to forgive Fredo, and so he did.
Fredo lived on the Corleone estate for however long, and then Michael had him killed.
So which brother betrayed the other more?
I say Michael betrayed Fredo more. What Fredo did was a mistake and he was mislead. Fredo was nothing without Michael, and Michael pretended to forgive Fredo. Fredo felt safe in their home, was bonding with his nephew, and Micael offed him.
My husband says Fredo put a hit out on the head of the Corleone family, whether he was mislead or not, and Michael's revenge was clever, as well as justified.