It is a very cathartic thing to do and something I have done it on occasion, but I do not do regularly. I do believe the process of writing it down helps to unload the mess from your head.
It sounds like you have had a rough time, so it will certainly do no harm to just to try it.
I have in the past tried 'talking therapies', but it just did not work for me at all, whereas writing it down and keeping it somewhere only I could see it was very helpful, I didn't share it. For me it was nothing fussy, nothing complicated, just a simple Word document. Others may prefer pen and paper to include sketches, doodles etc and may prefer to share it with others when they want to. There is no wrong or right, so just give it a go.