In my experience, it help me not think about it so much but also it made me think about everything more in a different way. I looked at things differently. I had to embrace the thoughts in order to calm my mind.
I definitely suggest you fast as long as you can because your mind will be able take a break because you won’t care as much about the break up, you’ll care more about not dying (you won’t but just an expression).
I suspect that it will. I know DF brings a sense of calmness from my experience. The only way to know is for you to give it a try. If you don’t have any experience with water fasting then it could be hard/difficult. It’s all about baby steps.
Do things that will strengthen your mental fortitude. Cold showers, dry fasting, 2-3 hour walk in nature(anti depression effect), eat diet rich in omega 3s that will help in mood, magnesium supplement to keep u relax