The Alienating Parent: Who does it, why they do it... 
Personally experience incidents are highlighted in purple
My comments are in red.

These articles and peer reviewed papers should bring some insight into the type of parent who alienates a child from the other parent.

Why they hurt their own children...

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Why do alienating parents do the horrific things they do? Don't they know the damage that they are doing to their own children? These are two questions that I get asked often. There are a number of reasons a parent will alienate their own children from the other loving parent. 
Go to this article and scroll down to "Parents who Induce Alienation to read more
Emotional Terrorist
There are so many articles and instances where I can say, YES! this is exactly what is going on. So many that  I don't bother to point them all out. But in this case I will. This is EXACTLY one of the things going on.
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Need to Conceal Parental Deficits (Click to read entire article)

According to Clawar and Rivlin, the campaign to alienate the child from the other parent is some­times used to deflect unwanted scrutiny of the programming parent's personal problems, for example alcohol, drugs, neglectful parenting, physical and sexual abuse, criminal involvement, or socially unaccepted life-style (7). Sometimes parents engage in PAS behavior out of fear that they will be found wanting when compared to the more loving and capable target. The literature on false allega­tions in divorce / custody disputes often makes the point that the accusation helps the accuser level the playing field, so to speak.
More about parents who alienate: 
A number of authors have commented on the extent to which the child’s enmeshment with parent A may co-occur with, and be predictive or even causal of the child’s rejection of Parent B (Gardner, 2006; Johnston, Walters & Olesen, 2005b). Johnston and colleagues (2005b, p. 204), for example, observe that,
“. . . parents who were alienating were also those who had poor boundaries and engaged in role reversal with their children. They had difficulty distinguishing their own feelings from those of their child, and the child often became the parent’s confidante, comforting and admonishing other family members, thus assuming an inappropriate executive or parenting role in the family.”
~from

PARENTAL ALIENATION AND THE DYNAMICS OF THE
ENMESHED PARENT–CHILD DYAD: ADULTIFICATION,
PARENTIFICATION, AND INFANTILIZATION
Benjamin D. Garber