De
verdad,
muchas
gracias
por
todo
lo
que
hiciste
por
mí.
deh behr-DAHD, MOO-chahs GRAH-syahs pohr TOH-doh loh keh ee-SEES-teh pohr MEE
Truly, thank you so much for everything you did for me.
"De verdad" (truly/really) at the start adds sincerity and emotional weight to your thanks.