You got mad as he had his hair cut, so you went and had sex with a friend of his
Crazy...thats all I can say. What would be next...he has a ring tone you dont like, so you go and hook up with his brother!?!?
As other people have rightly said, you're lucky hes even talking to you pleasantly.
Bite the bullet, ring him up, do what teenagers do... mumble and whatever, you know, down the phone at him, and ask if he wants to hang out in town, or whatever.
Worse he can say is "No"...and a few choice expletives