I have one of three reactions. By far the most common is I get an intense attack of giggles. The intensity and length of my giggle fit usually depends on the intensity of the sex. I've had to apologize more than once to a man who thought I was laughing at him. I just can't control them though. Very infrequently, one of two other reactions happen. I cry, just as you did........just burst out bawling and squalling like my heart is going to break. I think this has always happened after simultaneous orgasms. And, I also occasionally pass out, usually after a really intense orgasm.
Funny thing is, this happens online as well as real life. I've passed out a few times cybering. I get the giggles the rest of the time. I haven't ever cried online though, just real life.