At the end of season six (possible spoiler alert)

I think Plan C involved Andy calling the authorities and them catching Nancy (and in turn, Esteban) on the sly. Had she made a scene, Esteban and Guillermo could have easily made a break for it and came back for Nancy at a later time or put a hit on her in prison.

I think self-defense was a big part of it. However, Nancy was let out early because Esteban was murdered and she was no longer seen as in danger. I think a big part of her sentence was keeping her safe, away from Esteban and his workers.

Nancy went to prison for killing Pilar (taking the fall for Shane), not for selling drugs. I could see Esteban showing the tape and letting Shane go to prison, but what good would that really do him? With Nancy locked up, Esteban knew she would be miserable/away from her family/not able to move on with her life.

I don't think it is mentioned how he is in Copenhagen, but it can be assumed he either got the passport or applied for a new one and flew over after getting it. It's not specified how much longer the rest of the gang has been in Copenhagen at the beginning of seven, so we really don't know.

(Hope this helped, though some of it is speculation and not concrete fact.)

Any comment on how she only received a three year sentence for murder?