In perpetuum gratus ero, quamquam scio gratiam meam numquam comparabilis iri ad ea quae mihi dedisti. Amen.
Remarks about the translation
gratus/grata - masc./femin.
--- According to a bridge by lilian canale: "I will be forever grateful, even though I know my gratitude will never be anywhere near what you have given me. Amen'.