Doubtfuly or Doubtfully: How To spell?
The word Doubtfuly is misspelled against Doubtfully, an adverb meaning "In a doubtful manner."
Doubtfully has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings doubtfu & y which should not be misspelled with single 'L'
Wrong Spelling:  doubtfu-l-y  Correct Spelling:  doubtfu-ll-y 
Check more misspelled words of Doubtfully to spell it correct.