Choosing What To Think IV: Suppression vs Regulation

I’ve come across another piece of the “choose what to think” puzzle. Sometimes, things happen that make you sad, and it’s healthy and important to allow yourself to feel that sadness. Make yourself a cup of tea, put on some emo music, watch a supercut of sad scenes from Up on Youtube, have a bit of a cry under your duvet - that’s all good and normal. But I know that I have a tendency to wallow in that feeling, to let it consume and overwhelm me - to find comfort in it and then never want to leave. There is no catharsis in crying your eyes out to My Chemical Romance for the fifth night in a row, and some point it’s just an exercise in self-sabotage. There must be a threshold somewhere, at which I should no longer choose to pander to my sadness, I must accept it and move on - while sadness is part of life, I don’t deserve to be sad unnecessarily. There must be a line between emotional suppression (which I am very scared of doing, and so err far in the other direction) and emotional regulation (which I don’t feel like I do well at). It feels really important to try to find that distinction - perhaps even that it is an important component on the path towards improved mental health - but it’s not obvious to me where to draw said line, and I suspect the same is true for many other people.