There is more to this "story" than just what Mr. Schiavo is claiming: that Terri Schiavo didn't want to be kept alive by medical, or other means. He has apparently moved on with his life. He's bedding another woman while his legal and living spouse is hospitalized. It is clear to any impartial observer that Mr. Schiavo has no place in his life for his wife. While the logical course would be a divorce, Mr. Schiavo is intent on making sure she dies. Why. I think you know why.
Every day she shows signs of lucidity, he knows she could "snap out of it". There are charges that she didn't come to this predicament by an act of God, or a stroke of bad luck. There is medical evidence that something external happened to her. He fears he may be revealed as a batterer. As long as she breathes, he walks on shakey ground. Kill her, cremate her and he goes on.....free. The truth of what happened is justice fulfilled. She's still a living, breathing human being. with proper therapy, she could lead a more comfortable life. As long as breath and life remains in each one of us, hope lives. Without hope, living is Hell.
Only if she dies would anything that happened that long ago be relevant.
On the other hand, if there's been any misappropriation from her trust fund, that would establish a clear criminal motive for him to kill her (so as to avoid detection of his crime). Criminal motive + attempt to kill == attempted murder.