The Word ‘guys’ Has Landed Me In Trouble

Today at work I found myself in hot water for something I thought was politically correct. During a conversation with a female colleague I generalised her team members as guys, full comment I said: “We have two electrical testing areas, one at each end. But we should have one in the middle so it is easier for you guys.” Once that was said, my colleague then started shouting at me saying that she found the term “guys” offensive and that I should say “guys and girls” instead. I found that she was very defensive about this and I felt very uncomfortable with how angry she was getting. I apologised and said “I use the word guys as I find it includes everyone regardless of sex or gender, but is just a general term for a group of people, I didn’t mean any offence.” She ignored me and carried on her work, and a few moments later I was taken into a room with her and my manager. She was very angry saying I was using offensive terms as she did not like the word “guys” and no shouldn’t use it around her. I let her have her say in the matter and let her speak without interruption. Once she was finished I tried to explain myself, saying that I was used to using that term as I teach outside of not normal job and that is the politically correct term to use as it doesn’t segregate anyone. Before. I could even explain she kept cutting me off, shouting at me, swearing at me, even calling me the C word which is very offensive. Now I am being investigated and all the managers in the area are looking into it. I am now very concerned for my job as I feel the word I used was correct and that she was actually using the offensive language. I am more than willing to apologise but she keeps easing it higher to get me in trouble. I don’t know what could happen and I am not ever sure if I am in the right. Any advice or help?