My original thought being a rookie in this type of sleuthing, is she either did one of two things at this point in time for Caylee to be dead.
The duct tape suggests intentions to harm or make someone to be quiet, possibly kill someone.
The heart on the tape means regret/or a cute way to say I love you at Valentines day by decorating to identify? (sad)
The regret because she didn't mean to kill Caylee or she felt bad because her life was worth more at that point, after her past last months/days with the family and dealing with her actions were strained. And here's Tone. Or "I'm Sorry, Caylee it's all about me episode & I've had enough?" Just thinking aloud.
I do believe if her family had let her talk, she would have. Feels like some ideas of what happened in this case were put in her mouth. Other times, KC seems to be ready to mistruth her way out of it. Can't imagine playing that game with an adult child.