I guess right here I'm more like confessing my sins than asking for advice-- I really feel like I've messed things up irreversibly. But advice is definitely appreciated, definitely.

Mike has been my best friend since high school (five years). Just last year things got really strained between us, when I tried to take our relationship to another level. It didn't work out, we ended up not "officially" getting together, and we started seeing other people. But since then, things haven't gone back to normal.

We have been getting into petty little fights constantly-- usually over a misunderstanding, and one of us slams down the phone and sulks like a nine-year-old girl until the other calls again and apologizes profusely, and by the end of the night all is well again. Over the past couple of months though, it's becoming increasingly difficult to reconcile with each other.

Last June, Mike snapped at me when I called him because he wasn't in the mood to talk to me, so I refused to talk to him unless he called me first. We didn't speak until he called me on my birthday a month later.

Just last Friday, I was talking to him online and I made a joke at his expense, and he blew up at me. He blocked all of my screen names (that he knows about), refused to accept my calls for the past week nearly. I asked my sister to message him for me to let him know that I wanted to apologize, and he told her to tell me that he didn't want to hear it.

As far as the joke I made at his expense: it's something I've joked about at him occasionally before, and he's never been this upset with me. Annoyed, yes, but never really bothered about it-- at least, if he was, I never knew it.

Another factor in this whole messed up situation, which I think might be significant, is that twice since last summer Mike and I have messed around... behind his SO's back. After the second time I told Mike that I refused to be alone with him, not again for a long time, if ever again.

I called him a couple of hours ago today, only to have him pick up the phone and slam it down again instead of answering for me. It really kills me that he's not even interested in fixing this. I can't imagine not having him as a friend anymore.

Honestly, it sounds to me like it would be awfully hard to patch things up with him. I know it's MUCH easier said than done, but I'd try to move on. I know if I was in your situation I would be pissed if someone offered me such cliché advice but I just don't see how everything could work out. Plus, it kind of sounds like he is purposelly blowing things out of proportion as a way to "drop a hint".
I'm sorry, I hope things work out better for you.

If he is a real friend things will work out. If not move on - your post sounds more like a relationship than a friendship. If you two argue all the time maybe you are not compatible as friends or anything else. Believe me there will always be more best friends in the future.