Why do I have to prove I am innocent ?

Aren't you presumed innocent until proven guilty? Why when I have been wrongly accused of crime by an employer - how come I had to get indicted and then prove my innocense costing us a fortune. And the accusers do not have to do a thing. I have been to pre-trials 5 times already and the former employer does not even have to show the evidence they have - the prosecutor just keeps getting things pushed to different dates - this is killing me, and my family. I just don't get it.