Your not crazy. Sometimes the mind can just dissociate from the present moment if what is happening for us in the present moment is too much. Which is why higher levels of stress can sometimes trigger it. Mindfulness can be a really helpful tool to use to help you remain in the present moment. Mindfulness is basically allowing yourself to be aware in the present moment and to not to be caught up in the struggle but to rather let it sit there.
So a way of practising mindfulness in the situation you were in would be to notice what is going on for you in the here and now. So what thoughts your having, what your feeling, what sensations you are feeling in your body, what you can hear around you, what you can see and what you can feel. The idea is to just name it though rather than getting caught up in it. So for example naming anger and that you feel sweaty. There is some other mindfulness exercises
here that you might find helpful. Take care