Jesse James and Sandra Bullock at a post-Oscars party. (WENN.com)

A second woman who alleges she romanced Jesse James has apologized to his actress wife Sandra Bullock for the heartache her revelations have caused.

Melissa Smith came forward with claims of a long-term affair with the TV mechanic shortly after tattooed porn star Michelle McGee hit headlines across the world in March when she went public with allegations of an 11-month relationship with James.

The Blind Side star walked out on her husband shortly after the scandal broke - and Smith admits she'll "never forgive" herself for jeopardising their marriage.

In a letter faxed to Bullock's agent on Sunday, Smith writes, "I felt I needed to reach out to you and tell you how deeply sorry I am for everything that you've been through... And I know nothing I can say in this letter is going to make the pain of my actions go away.

"I am sorry for any hurt or pain that I have caused you. My actions of engaging with a married man are unforgivable. I never meant you any harm. I compromised my beliefs on several occasions and as a result will never forgive myself."

The letter, obtained by TMZ.com, concludes with, "Please contact me if you wish to discuss on the phone or in person."

McGee issued a public apology to Bullock earlier this month, telling the actress, "I'm sorry for your embarrassment. I'm sorry all this is public. I'm sorry for everything."

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