I think Christina helped with clean up. She may or may not have helped with the murder. But, I don't know that it can be proven beyong a reasonable doubt that she did anything but wait a long time to turn information over to the police.
I think she cut a deal and that is why LE has taken the line that she is cooperating and no charges are being fired.
I think Christina and CL were probably up all night conjuring up a story which would point away from Christine before CL fled. As bad as the story is, whatever the real timeline, through the note Christina is alibied when the murder happened. According to her and her husband's note Christina, didn't know about the murder until the Jan. 10. It can't be proved otherwise, either.
Once CL is caught, as long as he sticks to the story he wrote in that note, Christina is the prosecutor's star witness.
I think most of us think she had more participation that that, but, I think Christina made a deal all are satisfied with and will be free to move and start her life over eventually.