Of course you were devastated! The person you loved and trusted the most betrayed that trust in one of the most terrible ways possible by abusing the children he was expected to love and protect.
There’s an old saying, “Once burned, twice shy.” After a betrayal like that, most people have trouble trusting again. You are not alone. Not being able to easily trust doesn’t mean there is something fundamentally wrong with you.
You didn’t mention if you have been in therapy. If not, I encourage you to find a therapist who specializes in treatment of trauma. By working with a therapist, you will be able to recover from the past and refine your instincts so you can feel confident in your choices about who to trust.
You might also find it useful to join the PTSD forum here on PsychCentral.com (http://forums.psychcentral.com/). There you will find support and suggestions from others who are also struggling with the consequences of abuse in their families.
I wish you well.