Nowadays people have got the idea that writing helps one emotionally.Sometimes they have carried out experiments on groups of people and found the immune system was better on those who expressed their problems in writing.The scientific way is one way to look at it or we can use our experience,
With trauma writing or talking about it soo soon can make you feel worse.If it is an emotion like sorrow or anxiety it may help simply because if you start writing it is a form of distraction.
Apparently writing in form is better than free verse as it creates a psychological container for the emotions.I read Sylvia Plath might have been less depressed if she had written in form in her last year We can’t prove that
Another idea I have had is to use the energy of the emotion in your writing but write about something else.Using the energy is good for you.I think.I have done this and it helps because when we are upset we need to soothe ourselves.Some people clean out a drawer, for example.So if you write a letter about something different the act of writing has a soothing effect.I assume you will not write a nasty letter or email as you will feel worse and upset the other person.
Poets have a higher suicide rate than other people but it’s hard to know what is cause and what is effect.
All writers spend a lot of time alone.Leonard Cohen needed that and it made his relationships hard for his partners so often they left him.He suffered from ssevere depression but said suicide was undignified!He managed to have a long career and certainly shared his feelings of love and loss and about politics.