Fighting with boyfriend of 5 mnths..help??

Last night my boyfriend was at my house and we're always mucking around punching and hitting each other (lol sounds bad doesn't it?) but it's all in good fun! Anyway last night we were pretend fighting like always and I accidentally whacked him on the face, which I DID NOT mean to do. He got really shitty, walked out and sped off. I was just in shock so I couldn't do anything. I felt so bad that I couldn't sleep all night, and I sent him an sms apologising. I didn't hear from him all day, even after calling 100times ,which is unusual for him. Then sends me an sms at 6.30pm asking me to come by 7 or else it was over. I hate ultimatums! But I decided to call him 15 mins l8r, and he didn't answer. I called him so many times, yet he didn't answer. So I got my friend to call him & he said he didnt wana talk 2 me until 2mro. We've never had a big fight b4, so I'm really upset & worried! What should I do?