How can I address a fail in course when applyin graduate schools?
Since 3.53 is a rather good GPA, I would say nothing about the failed course. To say something would draw attention to it, whereas with the 3.53 GPA, many evaluators would not even notice that you failed one course. 

If I were a careful evaluator who noticed that one failed course, I would also notice your above-3.53 average on everything else, and would probably consider that very atypical (in the sense that I would guess that something unusually bad happened in that one case). If I really cared, then I would ask you about it in an interview; otherwise, the rest of your good record would lead me to give you the benefit of a doubt.

Of course, you cannot assume that every evaluator would take the same attitude as me, a random person on Academia Stack Exchange, but I do think that if you said anything at all (e.g. trying to excuse yourself in your motivation letter), you risk drawing attention to a negative detail that many people would not notice anyway.

Regardless, best wishes on your applications.