Will we be excommunicated for breaking the law of chasity?

My husband and I had a threesome with another woman like 6 months ago. I really didnt think we were breaking the law of chasity at the time. Being that we did it together. I only been a member for a year. But I starting to realize that we did break it. I did for my husband to keep him happy. I since then been praying , fasting and seeking forgiveness. I feel that I have recieved forgiveness from my heavenly father. I vowed to never do it again. I spoke with my husband and we agreed to never do it again. it happened one time. I since then has gotten so much closer to the lord. I am acutallly doing better now then before it happened. My faith is higher. I am not sure if i have to tell my bishop about this. Cause we are preparing to go to the temple.I am currently living my life worthy of going. I know i need that strength and the blessing from the temple and I know that I am more than able to keep my convenants that I wll be making in the temple. Should we tell the bishop or keep it to our self since me and my husband has moved on and we are living worthy now. if was in the past and I know that the lord has forgiven me , do i still must tell the bishop. I feel that if we do it will mess up everything that we have going now. We were not in full uinderstanding of the law of chasity, I thought that since we were married and i allowed him to do it it was not wrong. but later of course the spirit lead me to find out it was wrong. What do I do?