Killing is okay in marriage

I got a letter from a missionary friend of mine, serving in Ventura, today. She's learning Spanish while in the field (she went out as an English speaking missionary). She shared the following and I just thought it was too funny not to share:

"We have had a lot of miracle happen in this past week. We both have always had companions that have known the language really well. We aren't one of those. So, I am excited to be learning with someone. It was funny because last week we were teaching a lady the 10 commandments. I was thinking we were on the chastity/adultery one. Well we were really on the not killing on. I start going off on how this is something that is for after marriage. It's only between you and your husband. I pretty much said it was OK to kill her husband...and they were having marriage problems. It was corrected quickly and she ended up coming to church that Sunday....hahaha that just goes to show that it was the spirit that taught her and not me. "