<human>: Can you condense the text into a few key points?

So last night, bf and I were watching tv. I walked in front of his tv and accidentally kicked the plug out of the power strip. He muttered "bitch". I was shocked and fixed it up right away. I said something about "well jeez everyone makes mistakes". Then he like did a frustrated sigh. I asked about it and he was like "I was just joking, you're just too sensitive." I dropped it because he seemed so angry and I figured it wasn't worth pursuing.

And tonight, he said something related to the word bitch and then started going on about how I thought the word means more than it does.  I took that opportunity to bring up what happened yesterday night and he did that frustrated sigh again and said that he was only joking, originally said it in his "joking" voice (which I don't remember, it sounded like a frustrated tone to me) and that I was too sensitive. I said you know it's a legitimate wonder of mine, because I heard it and it did not sound like a joke, and he didn't respond to that, and turned the tv back on. After that show was over he acts like everything is normal, and right now I am still really unsettled and disturbed by this.

 This is not the first time something like this has happened, while the word bitch was never used before, usually my gender was the focus/target.

How do I address this with him? I need to know that I can speak to him about anything going on in our relationship otherwise how can we build a life together (that he says he wants)? I am very frustrated that he just shuts down communication in spats like that instead of explaining himself or sharing his perspective. And frankly, him getting angry and shutting down makes him look more suspicious/malicious than if he had just opened up and let me know what his thought process was, or what he is feeling about the situation.

What is my best strategy for getting through to him that it is important for us to keep communicating even when we are speaking about uncomfortable things? Any advice is appreciated.
<bot>: Boyfriend has a pattern of shutting down communication when I try to speak to him about something that bothers me-most recently when he "jokingly" called me a bitch for accidentally kicking out the plug to his tv.