Meditation really is a good tool, but I think trying to use it against anything -- as for example, sorrow -- is a mistake. The same goes for trying to use it for anything. I'm not entirely sure what this tool is good for -- it just seems to be a good tool.
When sadness comes, I guess it's time to be sad. Boiled down, it's just sadness and you have survived sadness before. Wishing, hoping or expecting sadness to be something else -- as, for example, joy, bliss, enlightenment, compassion or a chocolate bar -- seems to be a bit like trying to douse a fire with gasoline/petrol: The ache of sadness merely gets worse. Not asking sadness to be something else seems to be the only recourse.
Of course, maybe a little meditation might help. Or not. Breathe in, breathe out.
Is the sadness sad?