My most embarassing moment

This situation happened some time ago. I was at the American embassy for my American citizenship interview. I was reading when a lady asked me to help her understand the official who was to interview her. I started well, but then I started speaking Spanish with the person I supposed to interpret and English with the person I supposed to translate. Both ladies started looking at me, and none of them understood what I was saying. Then, I noticed they were looking at me without understanding what I was talking about. I realized my confusion. I started laughing uncontrollably. They started laughing too, but I turned red. I was really embarrassed for mixing languages. The good thing about this incident is that the lady didn't have a complete interview because of my mistake. In the end, it was funny. The lady who was doing the interview had a very good sense of humor, that she didn't finish with her questions. She just signed the applications in a very good mood. The lady who I helped sighed with relieving, and I kept laughing quietly. It always makes me nervous to translate.