Depp has confessed to substance abuse issues, is seen slamming cupboard doors on video, and wrote really mean texts, although the violent references were quotes from Monty Python, so not exactly the same as literal threats. One of the more damning statements he made to the marriage counselor is that "she gave as good as she got", and at first I thought that was an admission of guilt, but that statement was jotted down in the counselor's notes without context, and he may have been describing Amber in general terms and not personalizing it to their own relationship because he maintains his innocence of never hitting her. Counselors are required to be advocates for all of their clients, so a marriage counselor would be outside her ethical boundaries to take an actual side in a conflict. She has to support both parties in her statements.
Amber is on tape admitting to hitting and slapping Johnny, and he had to go to the ER when she severed his finger with a vodka bottle. Several witnesses describe her throwing objects at him. She also has a history of hitting her sister to leave physical injury, spat in the face of her assistant, and pooped in his bed.
There are few people who would not respond to her behavior with angry texts, name calling, or slamming cupboards. Most people online become way meaner textually with far less provocation. I would personally be very hurt by texts like Johnny made, but I also don't throw things at people, hit them, spit in their faces, poop in their beds, or demean them verbally.