Yes, Newt's personal life and personal history kept him from being a serious candidate for the presidency. However, I don't think that it was the Democrats that did him in, certainly not folks close to Hillary.
Gingritch was in a Republican primary with many, many conservative candidates for folks to choose from. Folks simply looked elsewhere, most notably to Santorum. Of course, Santorum was not a very good candidate, and had little chance. In the end, Newt's personal history didn't play well with the religious right. If there weren't so many choices, perhaps Newt would have been more acceptable.
Also, we need to remember that Newt left his leadership position in the 90's because he could no longer get along with the far right of his party, the very people he helped get elected. As is the case with many "true-blue" Reagan Republicans, Newt was simply no longer acceptable.