Sorrow is a tricky thing to write. Do too much and your characters just seem melodramatic. Do too little and they seem robotic. So what do you do?
First off, if you feel sorrowful yourself, use it. I’m sorry that you feel that way. Truly. But if you need to write something sad, you’re in the perfect mindset. You don’t need to imagine what a character is feeling because you’re feeling it yourself. Tailor your sadness to your character. Mold it. Refine it. In the end, you will have created something realistic and beautiful from something horrible.
With that said, I hope not all of you are sad, and I’ll offer you an idea of mine to help produce realistic emotion. For each of your characters, imagine them on a spectrum. Right now your character is on the middle of the spectrum. To the left of the character are negatives experiences and all their corresponding reactions, and to the right of the character are positive experiences and all their corresponding reactions. 
Don’t think about where exactly each experience is on the spectrum. “Stubbing a toe is two units to the left. Winning the lottery is fifteen units right. Falling down the stairs is six units to the left…” No. I just want you to think of each experience in comparison to others. If stubbing a toe produces this reaction, then what reaction will falling down the stairs produce? If a breakup produces this reaction, then what reaction will the death of a loved one produce?
Also, keep in mind that not all reactions will be the same across different characters. Some characters are more emotional and dramatic than others. Some are cold and stony up until a point. Be conscious of character’s limits. What makes a certain manly man becoming a sniveling child? How soon does a drama queen bitch and complain?
Sure, I’m not really telling you how to write sorrow. That’s up to you. I’m not going to tell you what sort of writing style is best. I merely want to give you context.
He Who Wanders 