Internal dialogue is common. (like when you think of just the right retort after it is too late to use it)---in depression, it is common to ruminate & get stuck in ruts. I have been there, am actually there again right now but it won't be forever.
What I find helps is to express myself---writing is good, but sometimes non-verbal creative activities are the very best at banishing the cud-chewing, bringing in the NOW and WOW of the small treasures in life---there is something about being able to represent feelings in action, whether physical activity, playing with paper/fabric/paint/whatnot---reminds me I should make a big batch of play dough for the grandkid...practical but much more satisfying than buying the thing. And, it is so much smoother, it will feel good to knead the colors into the dough...this thought takes me away for a time from the past...the what ifs, whys, blame game, the internal negotiations. ....if you can focus outside yourself, even on an animal, a tree, cooking a meal...it will interrupt the thoughts enough to at least let you know it is not "always".
[& i do think most of us have had the experience of driving or walking somewhere so well known, a path so well worn, that we are surprised by having missed so much of the journey, as if we were on automatic pilot, or "someone else" was travelling---it is a good reminder to pay attention...or to work at it...]