The correct wording is "tell them I'm a victim too of domestic violence." In other words, that it's a given fact between them that he was also violent towards her.
This was a conversation about his assault on her, which he has admitted to (although obviously minimising it). In the same conversation, she said she asked her friend Io to call the police because she really thought she was going to lose her life, and he would do it by accident.
Further context from a little later in the conversation:
"I'm just trying to point out the fact of why I said call 911 was because you had your hands on me after you threw a phone in my face, and it has gotten crazy in the past, and I truly thought, I need to stop this madness before I get hurt."
You can debate about reactive violence but you need to take into account that she had been in therapy for years at this point and her therapist was trying to help Amber Heard to leave because she was scared for her safety, based on Heard's description of the relationship over that time period, mainly based on Depp's jealousy and his behaviour while taking drugs and drinking. She didn't want to leave and she didn't want to get him in trouble or see herself as a victim. Which is very common.
Case in point re jealousy: the messages he wrote on the walls in Australia in blood, which show he was paranoid about her co-stars (Billy Bob Thornton)
So we know that Depp was violent, jealous and paranoid from an early point in the relationship. We also know he sent texts early in their relationship because she was 'nagging' him about his drug habits, expressing a desire to drown, burn and rape her corpse.
In other recordings, he says he headbutted her in the forehead, in another one she says she left for a while after he "beat the shit out of" her, and there's a whole text conversation with his assistant about Depp kicking her in front of a group of onlookers while blackout drunk/high on a private plane.
The conversation about her hitting him, she explains she hit him because he'd hurt her toes and she freaked out thinking they were "going there".
All of which is very normal in relationships where there is violence and trauma bonding.
Basing your view of an entire relationship on a few recordings made after years of being conditioned by domestic abuse, and her being argumentative rather than meek and cowed, is ridiculous.
Anyway, I just wanted to put that out there because while I don't doubt women can be abusive, I'm sick of the misogynistic narrative about Amber Heard, and the way snippets of recordings are presented out of context to further that. At least other people can see there is a lot more to it than that, since you seem to have omitted those facts.
I'm not going to post here anymore, I wish you the best OP with your healing.