Boyfriend says I'm a slut for letting this guy hit on me

Me and my boyfriend were at Ross. I shop their all the time and they hired a new cashier. He looked like he was maybe 18, possibly still in high school. I'm 19. Me and my boyfriend were looking for stuff for our new apartment. I asked him where stuff was and this cashier said " Your hair reminds me of fluttershy!" I had my hair died pink. I laughed and he started asking me if I knew who Twilight sparkle was and all the other my little ponies. He showed me the my little pony pins on his lanyard. He said his favorite was Rarity. Well my boyfriend git ma and yelled at him for flirting with me... I told him to calm down and he said I'm a slut who likes it when guys flirt with them. He asked to speak to a manager who was near by and he pointed to that poor cashier and said "How about hire people who don't sexually harass others girlfriends". So then he made that poor guy cry and an associate near by had to get him to walk him tonthe back.. and it was horrible. He apologized an hour after we got home. He said he's under a lot of pressure and snapped. Honestly I'm thinking about making him prove he's sorry by going and apologizing to that cashier.

Me and him have been together 3 years and he's not usually like this. I know what he did was horrible which is why I'm wanting to ask him to apologize to the poor guy. I'm not trying to assume anything but just how he was talking he sounded like he my have been special needs which I hope is not true because that makes this worse