If you were a child and your parent called you disgusting filth that deserves to die on a regular basis, I doubt you would much care about the distinction between physical and emotional harm.
The law cares about the distinction, and with good reason. The former interferes with the person's free exercise of their natural rights, whereas the latter does not. Sure the latter can cause someone to feel bad or become depressed, but if that's our standard then any kind of harsh or critical language would constitute an act of violence, which unreasonably debases the word.
That's the thing though, that term "natural rights", in reality, a human being's "natural" rights are only really what society accepts them to be, rather than being something inherently ordained by nature.
The kind of sustained, psychological and emotional abuse very much does cause signiifcantly more harm than a punch up outside a bar; and if the law, or society, don't see it as being at least an equivalent level of violence than that is probably more down to the legal or social norms not keeping pace.
There is a quantative difference between a simpl act of harsh/critical language and between psychological abuse - just as much as there is between insulting someone and physically attacking them.