To believe that there is good in all people is noble. To believe that just because someone has some good in them that they will not harm you or yours (emotionally or physically) is dangerous.
You have a situation in which you don't want to believe something negative of someone else... I feel that and I'm sorry, because I know it's really disappointing
I really give you a lot of credit for being able to look beyond your own point of view. It's actually a strength to be able to say, "Hey, check my blind spot," you know?