If you are involved in a similar situation, I strongly, strongly recommend engaging in counseling therapy, and to visit the following blog sites for in-depth articles and discussion on betrayals and convoluted behaviors and thinking:
www.180rule.com
www.familyarrested.com
This type of situation is not as uncommon as you might think, but it's rarely ever discussed because it's such a dreadful betrayal that the victims typically believe that nobody will support them, and that they somehow "did something" to deserve such a betrayal.