It's a very common tactic of abusive men to turn things around and make out like he is the victim. People who work with DV victims are sadly all too aware of this tactic.
Obviously I don't know what happened throughout their relationship but when I heard about this lawsuit my first reaction was that he was using this tactic to continue to assert power over her. Logically if she was the abusive one and he had evidence of that then he would have made this clear when she started to make allegations against him and not three years later when everyone else involved had moved on. Why is this evidence only making an appearance now? Surely if his claims are true then he would have had evidence back then so why didn't he present it then? It doesn't make sense.
I know photos have appeared showing Depp with bruises and a severed finger which he alleges were injuries caused by Heard being violent towards him but there were also photos of Heard with suspicious bruises throughout their relationship. I remember at the time there were people questioning the bruises and doubting Heard's story around the iphone bruise under her eye so why photos of Depp's injuries and how he claimed to have gotten them are just being accepted as fact and not being held under scrutiny and questioned like hers were is beyond me. And again, why have these photos only emerged now? If they were taken during his relationship then he would have had them at the time this whole thing first started. He could have released them back then to prove Heard was the abusive one but he didn't. That looks very suspicious to me.
Perhaps Heard did admit to being violent towards him but what was the context? Did she admit to hitting him unprovoked or was it a case of her lashing out in self defence after being on the receiving end of abuse from him? It's a very difficult thing to judge because all we know is that she admitted to being violent towards him but with no context given.
People who are being abused rarely do absolutely nothing about it. It's not unheard of for a woman who is a victim of domestic violence to lash out at her abusive partner in self defence which the partner will then turn around to make it look like she was the abuser. How do we know this isn't what happened and is happening here?
What I will say however is that I really hope she didn't make any false accusations because if it comes out in the wash that everything was a lie then we'll never hear the end of the cries of how women lie, she has done a massive injustice to real victims, etc.