Six words of varying degrees of sadness and pain: 痛心, 悲伤, 伤心, 难过, 难受, 伤感. https://blog.lingobus.com/chinese-learning-resources/

1. Here are six listed in approximate order, from grief down to sentimental
melancholy:
1. 痛心 / tòngxīn
Literally “ache/pain + heart”
痛心 is commonly used when referring to anguish, grief and regret.
Used following tragic or terrible events. Examples:
Zhè jiā rén duì tāmen de sǔnshī gǎndào tòngxīn.
这家人对他们的损失感到很痛心。
The family was feeling deep sorrow for their loss.
Wǒmen dōu hé nǐ yíyàng tòngxīn.
我们都和你一样痛心.
We all share your great sadness.
2. 悲伤 / bēishāng
Literally “sad + hurt”
On a scale from 1-10, 痛心 is 9, whereas 悲伤 would be less severe,
about 6 or 7. 悲伤 describes when we are deeply sad, perhaps about
loss of family or friend, or when lamenting about the past. Examples:
Wǒ cóngwèi tīngshuō guò rúcǐ bēishāng de shì le.
我从未听说过如此悲伤的事了
I’ve never heard of such a sad/sorrowful thing.
3. 伤心 / shāngxīn
Literally “injured + heart”
伤心 is the heartbreak we feel when a long relationship ends or even

2. when a loved one passes; it describes hurt and sorrow, but slightly less
severe than 悲伤. Examples:
Ta shífēn shāngxīn
他十分伤心
He’s totally heartbroken.
Zhège xiāoxi ràng tāmen hěn shāngxīn.
这个消息让他们很伤心。
They were broken-up by the news.
From
Sergiocarlos.net
4. 难过 / nánguò
Literally “difficult to get through”
难过 relates to emotional upset rather than full-on distress or
heartbreak like the 3 above. It’s used when we feel miserable or
emotionally uncomfortable about something. Examples:
Zuì nánguò de rìzi yě yǒu jìntóu.

3. 最难过的日子也有尽头。
Even the most difficult days have a limit (idiom)
Wǒ wèi tā gándào nánguò
我为他感到难过。
I feel sorry for him.
5. 难受 / nánshòu
Literally “difficult to accept/handle”
难受 is used interchangeably with 难过. It can also refer to
physical discomforts, such as illness or even wearing shoes that are
really tight. Examples:
Wǒ shēngbìng le, hěn nánshòu!
我生病了，很难受！
I’m sick, I feel lousy!
Nánshòu sǐ le!
难受死了
So painful/uncomfortable! (literally: uncomfortable to death)
6. 伤感 / shāng’gǎn
Literally “wounded +moved/touched”
This is an emotional, sentimental sadness or melancholy. 伤感 could
be used about saying goodbye or reflecting in past times. Soppy,
sentimental songs, poems or movies can be described as very 伤感.
Examples:
Tā búshèng shānggǎn.
他不胜伤感
He is overcome by melancholy.

4. A! nǐ bié shānggǎn le!
啊，你别伤感了!
Ah, don’t be sentimental!
So there we have it. Six words of varying degrees of sadness and pain:
痛心, 悲伤, 伤心, 难过, 难受, 伤感.