It's long and complicated, and the Penguin says it better than I could. If you don't wanna read it, that's your right. Here are two comments of my own, unrelated to that point.

1) the fact that lots of other men have treated women badly tells us nothing about Depp's guilt or innocence

2)I think there is something wrong with the idea that if a woman and a man get into a fight, the man is always the abuser and the woman is the victim. The testimony in the court seemed to me to indicate that Depp and Heard abused each other, and consequently labeling Depp as "the abuser" was false and libelous. That's why he won, and should have won.