What can i tell to my dad that i don't want him to marry that women that shes after his money?im 12 help :(?

It looks like your Dad is trying to prove to himself that he is not old (50 is a scary age). If they keep breaking up then I don't think your Dad will ever marry her. Tell your Dad there are other women nearer to his age and is not a sad case for him to be happy with in the future.