Oh hun..I don't really have any advice for you but you sound like you need some of these:

I do think there needs to be some serious consequences for lying to you about where he has been, that must have been so worrying not knowing where he was when he wasn't where he said he would be (say that 10 times fast..lol). So maybe no sleeping over/going to friend's houses at all for a while until he realises the severity of what he has done, maybe taking away some of his other priveleges such as tv/computer for a while as well.

I do think you, DH and your son need to sit down together and have a big talk, that what he has done is not ok and the reasons why you don't want him seeing this other boy.

I hope you can work it out, I think I can wait for the teenage years!