You might look at Twain's notebooks which can be most revealing of
his feelings not hidden behind a satrical veil.  In fact I can dimly recall
a passage or two but my copies of his notebooks are at my office and I will
not be back there the remainder of the week.  However, I did find in his
autobiography a passage that is similar to what I remember reading in his
diaries.  After describing the death of his dearest daughter in Chapter 71
Clemens writes: "She was the most beautiful spirit, and the highest and the
noblest I have known.  And now she is dead."
        Knowing Twain's love for his family and the pain he suffered from
their deaths I have always found this passage moving.  His simple yet
elegant description of her spirit followed by "she is dead" is a
juxtaposition of Samuel Clemens the writer and Mark Twain the man embittered
by life's circumstances and humanities cruelty.