Over at AskMen they had an interesting thread, "How cautious are you about disclosing your insecurities to your girlfriend?". Just google the title to find the thread.
Men reveal how cautious they are about their insecurities to their girlfriends and what happened when they opened up. Surprise, suprise - the results are as you excepted. Remember, these are men from the AskMen sub, so they are the average Billy in the street.
I used to be very open with my *ex gf until I found out she told some my secrets and insecurities to her friends. It was a "but I tell her everything!" situation. Here's the kicker, she later got pissed at me when she found out I told my friends about parts of my sex life (it was after we broke up and I didn't say any specific details about any partners, nobody would be able to figure out who I was talking about). Now I only really share with my closest bro.
9 times out of 10, whenever I opened up to a SO, the relationship fell apart shortly after. Women may say they want a man to be in touch with his feelings, but in my experience they'd "rather see me die on top of my white horse than watch me fall off". And I'm not even confessing anything of import. Just general life insecurities and such.
80% of the time I disclose an insecurity, it gets brought up against me in an argument that's not even relevant to said insecurity. It's doesn't matter if she apologizes, it's been said and the damage is done. I want to trust my partner and confide in them, but damn does it get hard sometimes
Lesson: Do not open up to any women. Do not trust any women. Have a close group of male friends whom you trust - they are the only ones you can speak with.