I feel terrible.
Flest

October 2021
I feel very bad
tbinder

October 2021
She feels terrible that her daughter is not talking to her and the general situation. This could be both a mental and physically feeling she is having.
ellaesa

October 2021
I think in this case, "I feel terrible" is expressing regret and not necessarily a physical feeling. Caller 1 is sorry that their actions caused their daughter not to speak to them. Caller 1 regrets upsetting their daughter.
evgueny40

October 2021
I feel terrible = I feel very bad, shocking, awful, very unpleasant.
I hope it helps to understand the sentence.