he cheated on his girlfriend with me..

About 6 months ago me and a guy where best friends and he'd FaceTime me everyday for about 3 hours and we'd talk. It was very nice and we where strictly just friends. Then he got angry one day and told me to f*ck off. 
Last week he apologized and he was very sincere. He's has a girlfriend for about 6 months, since after we stopped talking.
He asked to hang out and talk, but she couldn't find out. So we hung out and talked just like we used to.
Then this weekend he came over and he kissed me for the first time, he cheated on his girlfriend with me. Things got intense and we almost had sex but I told him no because he has a girlfriend. I would've been his first time too. 
What does this mean?