Answer:
The punctuation correction would improve the following sentence:
At first I felt very angry bitter and hateful but then I felt so hopeless and depressed. I longed for her to call me
Is:
a comma in
then, I felt
Step-by-step explanation:
The reason behind this is because it is a composed sentence, in other words, both can exist without the other. However, in this case, they complement each other to provide more information about the situation. But they are still two different ideas, therefore we need to specify that they are two different ideas. If we add a comma between then, and I. We are separating the ideas with a dependence without breaking the meaning or their consecutiveness.