Blowing stuff out of proportion

I met my girlfriend when I was twenty-one and over the years we've had our ups and downs. One of the serious downs was when we broke up a year after we got together because I, admittedly, was being an ass. Ever since she was little she lived next to this guy who obviously had a crush on her, and they were really close. She said she only liked him as a friend, but one night I couldn't get in contact with her, and she was at his place, I freaked out and was convinced she was cheating on me. It turns out that his mom died and she was only comforting him, which just made me look like a creep, but we broke up soon after because I couldn't admit I was wrong.