What should I do?

My husband cheated on me and that too on my best friend..I have been in the relationship for 6 long years and got married 7 months before and he revealed couple of days back that he cheated on me!! He and my so called BFF were fucking each other behind my back and it was very easy for them because we lived together..We went through hard time together, settled together and now I am confused what to do next after knowing the truth!! He said he will support my decision but I don’t know what step to take!!Help me out guys!!