There is no truth to the rumor, it is clearly, patently false.
There are many grounds to criticize Governor Palin's qualifications to hold public office. If she continues to highlight her children as some of them, that might include the effectiveness of the approach to parenting that she champions (and tries to codify in law.) But the sanctity of her own marriage to her husband Todd is not.
Folks, please discourage your friends and acquaintances from pursuing this any further. Stick to the actual, documentable issues. It's fertile enough ground--a petty, vindictive, fiscally-irresponsible, power-mad Christianist is no public servant worth having.