He makes a big deal over EVERYTHING!

Lately my boyfriend has been making a big deal put of a lot of things and today he just took it way out of proportion and doesn't understand why it's not a big deal. An old best friend of mine messaged me on fb saying another one of our friends wants to get together with our old guy best friend. Well I happened to date the guy in middle school during 7th and 8th grade. But never once did I even kiss the boy so it's not even a real relationship. Well my bf got mad because I even considered hanging out with an ex even though I told him it was middle school and I'm now 21 years old and haven't talked to the guy since like my freshman year of high school. He then sat there and asked how I'd feel if he went and hung out with one of his exes from middle school, mind you HE WAS HAVING SEX IN MIDDLE SCHOOL I WASN'T! So it's completely different and he tried saying it wasn't! HE HAD SEX WITH THEM! He doesn't understand that it wasn't even a real relationship cause I wasn't having sex with the guy! I don't freak out over the fact that he's had sex with 10 girls when I've had sex with the guy I lost my virginity to and him! Only 2 guys! But yet it's a big deal to reconnect with old friends. I'd completely understand if I was saying I was going to go hang out with the ex I lost my virginity to but it's not a guy I had sex with! Do you guys think he's over reacting or am I not understanding where he's coming from?!