Why would my husband get so angry over a pin that I asked where it came from and he tried to say it was mine.?

When he answeared he gave attitude. I said it wasnt mine and that if a girl gave it to him well as long as he wasnt screwing around. He got quiet but that I am pissed quiet, I dropped the subject later I asked him what was wrong he eventually said it was the button and that I said he was screwing around I never said he was. I guess I sort of insinuated but never really accusing or even getting angry, he on the other hand ended up yelling ang going on about the pin and how he didnt know and that I accused him and I dont trust him . Yes he has cheated previously, about 6 months ago, I said even with everything I am supposed to completely trust him I had done that before and look at what I got. Its hard for me to trust he is at work when he says he is or that no one is in my home when I am at work and no til tonite I didnt share that info with him-- he turned around and said how do I know your at work when you say you are you have the car. I have never cheated on my husband and I kept pretty calm during all this and he kept getting angrier, should I belive that he has no idea about the pin .