You're not the first person who has been burned by someone you trust.

I would tell you that you have to keep trying to build trust because losing trust in humanity after two critical incidents is foolish, but I'm not going to. If I did, I'd feel like a hypocrite.

You see, I've been burned by many people too. Now I realize most of them were well intentioned, but they were not very bright (my parents included). After years of getting burned, I finally decided I have better judgment than those in my social environment, so I stopped trusting them.

I live my life without trusting anyone. I will ask for advice and general information, but if the person giving it seems slightly uninformed, I was ALWAYS make the decision myself. (Regardless of any status or education differences)

Now, I don't advocate this way of living. I truly believe that a person needs to trust others and form stable, secure relationships in order to be truly happy.

As for me, I've been warped by years of depression, so I learned to embrace the solitude. I know I should change, but I'm so stubborn, I probably won't. (I'm one of those crazy, emotionally shielded people. It's actually pretty dysfunctional.)

Good luck coming to terms with this issue. Believe me, it is a struggle you'll have to resolve one way or another. Sometimes it's good to trust others, but there's nothing wrong with "double-checking" their decisions.

On a side note:
This is the exact issue which precipitated my first depression. My IQ is in the third standard deviation, and my parents and those around me have a "normal" or low IQ. Obviously, this presents a problem. I'm still trying to fix the damage. It's one thing to know what's wrong with you, but it's much more difficult to actually change it.