I want to divorce

is there someone who can tell me if i can divorce with my hu*****and?
i came to America in March this year with K1 visa, which is fiance visa. Now i have passed the interview in INS and i am waiting for the green card.
my hu*****and makes me so dissappointed. he keeps going out with a girl and never care about my feeling. we often argue... i am so sad.
can i divorce? and do i have to leave America if i divorce?