Diddy's 45th Bday Scrapbook Letter From Ex-Assistant 'Mia,' New Trial Exhibit

Diddy's defense made a big deal in court about a scrapbook one of his former assistants -- who testified Diddy raped her -- says she made for his birthday ... and now we're seeing it for the first time.

The ex-assistant, who took the stand under the pseudonym "Mia," testified about making a scrapbook for Diddy's 45th trip around the sun ... Diddy's defense attorney Brian Steel showed it to jurors back in May, and it's now been entered into the public record as a defense exhibit.

The scrapbook features a glowing letter to Diddy ... with Mia writing at the end, "I love you forever and eva and eva."

Diddy's defense grilled Mia about the scrapbook, questioning why she would make a loving birthday tribute to a man she testified raped and sexually assaulted her. She testified he first assaulted her during his 40th birthday party.

Mia told jurors she made the scrapbook because Diddy had come to her "depressed" and "sad" and she wanted to remind him his life and his successes weren't meaningless.