Shrinking Database Task
Do not use the SHRINK option.

It results in serious performance degradation. Also after you shrink the data file, it will later grow even more. 

Please watch this video by Klaus Aschenbrenner (Microsoft Certified Master in SQL Server):

SQL Server Quickie - SHRINK

I would recommend to kill the SPID but be ready for the rollback operation. It can take another 3 hours, maybe less.