Speakerphone Embarrassment

A few weeks ago, I was talking to one of my co-workers about several projects we had been working on in the past few months. I put her on speakerphone so that I could have both hands free for pulling up data on my desk PC. A few minutes later, another co-worker entered my office with a report pertaining to one of our projects which we had been anxiously awaiting. The co-worker who handed me the report was silent, seeing that I was on the phone. I told the co-worker I was on the phone with that I had just received the report from the other co-worker, to which she relied "He really creeps me out, for some reason". Of course, the co-worker in question heard her say that, and there I was sitting their with my mouth agape at what had just happened. I looked at him and before I could say anything, my co-worker on the phone went into a tirade, criticizing this man for his demeanor while he was standing there listening to every word. I stopped her and said that I would have to call her back as I was needed down the hall. Needless to say, I was thoroughly embarrassed and apologized profusely for her behavior. I told him that I certainly didn't feel that way or agree with her and that I hoped her saying those things would not give him a bad impression of me. I could tell he was upset, having just heard that someone disliked him for being himself, and I felt awful about the whole incident. After he left my office, I then started to think of how I had failed mention that he was in my office to my co-worker on the phone. I felt completely responsible for what would now be a strained relationship at best between those two. I now only use the speakerphone option during meetings. I never heard any more from him in regard to the situation, nor did I ever tell my other co-worker that he had heard what she said. Despite nothing really happening, I plan to play it safe next time to avoid being sorry. Maybe I'll get a headset for those times when I need both hands free. Anything which could help to avoid having a situation like that happen again is a smart idea.