Yesterday, we brought you an exclusive interview with Ashley Kaufmann, whose mother claims she is actress Lindsay Lohan's secret half-sister. Tonight, Ashley reveals the letters signed "Love, Daddy," and the broken promises the man she claims is their dad, Michael Lohan, made to her as she was growing up!

"He's always hurt me," she says through tears. "It's been throughout my life."

Ashley's mother, Kristi, says that the 13-year-old is the offspring of a three- to four-week affair she had with Michael in 1994. 

"When he came back, I told him I was pregnant," she says. "I knew that he wasn't happy about it so I gave him the door ..."

Kristi claims that Michael kept in touch with Ashley as she was growing up, and tonight the two are showing us more than 20 letters, sent from jail and signed "XOXO," they say prove it! He's also taking a DNA test to determine paternity.

"I want Michael to stand up and do what he's promised all these years," Kristi says, while Ashley remarks: "I'd love to meet my siblings. I'd love that."

Watch the video and tune in tonight for more with Lindsay's alleged sister!