I married with US citizen in 11/2003. Apply 婚姻綠卡 in 12/2003. I got 婚姻綠卡 in 06/2004. Before 90 days of 3 years marriage, I applied 公民 in 03/2007. I become 公民 in 08/2007.
If you have 5 years of green card, just apply 公民 as normal which it is not related to you hu*****and.