Lyle Menendez's Wife Announces Separation After Cheating Speculation

Lyle Menendez has a major life update to share that has nothing to do with his possible release from prison ... his wife, Rebecca Sneed, has confirmed their separation.

Rebecca, who married Lyle in 2003, posted the relationship update on her husband's Facebook account Friday, sharing she and Lyle had been "separated for a while now."

However, she made it clear there's no bad blood between her and Lyle, clarifying their split was not prompted by "a cheating scandal" and "remain best friends and family."

There have been reports of Lyle having an affair with a 21-year-old student, named Milly Bucksey, who he was seen cozying up to during a visit behind bars. The two have allegedly been communicating via a cell phone amid LM's ongoing incarceration.

Rebecca maintains there's no illicit affair, emphasizing her dedication to Lyle and Erik's fight for freedom. She said she planned to keep Lyle's Facebook page updated and share news on his case ... reiterating her dedication to "never stop fighting for them."

Lyle is currently serving a life sentence alongside his brother, Erik Menendez, after the siblings murdered their parents, Kitty and Jose Menendez, in 1989.

Lyle and Erik are set to get a major update in their case today ... which makes the timing of Rebecca's announcement all the more interesting. A hearing is set for this morning, and we know their lawyer, Mark Geragos, will ask both that their sentences be reduced and the conviction be changed from murder to manslaughter.

Lyle had mentioned his upcoming 20th wedding anniversary in a resentencing request from earlier this month ... citing his marriage as a way his life has changed "in so many ways."