I think that it is after the salutation or before the closing of the letter. If it were a letter, it would look like this:
Dear Dr. Doctor,
(Dear is the Salutation). Body of letter. Body of letter. Body of letter. Body of letter. Body of letter. Body of letter. Body of letter. Body of letter. Body of letter. Body of letter.
Sincerely,
Brainly
Basically she is saying "i love you so much i would do anything for you and i will miss you until i see you again tomorrow."