You are absolutely right and your BF is completely over reacting.

Personally I think you need to be less apologetic. He is behaving terribly and you placating bad behaviour is not really helping.

You should say something like, "Apparently you and I had a miscommunication. I never lied to you but this issue comes completely down to personal evaluation of the situation. You think it is more than it is. I thought it was less.

It has zero impact on our relationship but your behaviour now is jepordizing it. If your belief in a conversation with a near stranger has greater value than your mate, then we have a problem.

The silent treatment is not acceptable to me. It is way overblown about something that happened when we barely started dating.

You either trust me or you don't about a situation that has absolutely no impact to our relationship. Which is it?

Time for a conversation about us moving past this.

Stop the thinking/sulking time. Either it is resolved or you misjudged his ability to be in a relationship.