Why does Tom attend Gatsby's party? What is deeply ironic in Tom's statement about his being old-fashioned and about the freedom of women?

http://www.gradesaver.com/the-great-gatsby/q-and-a/why-does-tom-go-to-gatsbys-party-77035/

The irony of Tom's statement can be found in the fact that his own wife is running around and associating with the "wrong kind of people." The same can be said for Tom himself.