Eptopic pregnancy, how long does it take for HcG to go back to zero?

Unfortunately this pregnancy was eptopic and ended this week at 6weeks resulting in losing one of my tubes also. It has been terrible tough and such a shock going from extreme happiness to the opposite. We had a tubal reversal in May this year and knew there was a risk. We fell pregnant the second month trying and were over the moon. Not sure how my other tube is yet. My question is has anyone gone through this and do you know how long it takes for HCG goes from back to zero. I was over 6000 prior to the op. Any information would be greatly appreciate.