truly

truly /ˈtruːli/ adverb
truly
/ˈtruːli/
adverb
Britannica Dictionary definition of TRULY
[more truly; most truly]
1 
: in an honest manner : sincerely
2 
: in truth : actually or really
3 
: without question or doubt — used to make a statement more definite or forceful

yours truly

1 
— used at the end of a letter and before the writer's signature
2 
humorous — used to refer to yourself