Losing your mother is a terrible thing and I don't know DeAngelo Williams personally, so I'm would not dare assume that he would do something as terrible as lie about it for his own gain. Regardless, context is everything and the timing of this from him is disappointing and exploitative towards the fans and this franchise.
I feel for his loss. I can't respect how he brought it up on his way out the door like a scorned lover instead of mentioning it at any point during the nine illustrious years he had with the franchise, including public moments the franchise specifically dedicated to his mother. It hurts as a fan because I thought he was better than that.