What is the overall tone of this excerpt from "When We Two Parted" by Lord Byron?

They name thee before me,
A knell to mine ear;
A shudder comes o'er me—
Why wert thou so dear?
They know not I knew thee,
Who knew thee too well:--
Long, long shall I rue thee,
Too deeply to tell.

In secret we met—
In silence I grieve,
That thy heart could forget,
Thy spirit deceive.
If I should meet thee
After long years,
How should I greet thee!--
With silence and tears.

A.
somber
B.
distressful
C.
bittersweet
D.
joyful