Daily Mail scoops the story, pictures of the husband, apparently he was a weightlifting type or something like that. http://www.dailymail.co.uk/news/article-2581481/Married-mother-two-admits-killed-weightlifter-husband-poisoning-steroids-anti-freeze-just-months-pining-love-Facebook.html
From the article: The 42-year-old man was a competitive weightlifter who worked as an environmental specialist at the DuPont Experimental Station. He and Jamie were married for 21 years.
From the pics at the link, he's 42, looks 30, handsome and in excellent physical shape. She's 44, but her face looks like that of a 60 year old.
I'm guessing she realized that he could dump her and easily replace her with a cute 20-something women, and couldn't deal with it. Or perhaps it was for the insurance money.