I Need A Little Help

So, a bit back my best guy friend, whom was like a brother to me, moved away and i posted a journal about it asking for a little advice on what to do to cope. Now, he e-mails me saying he's moving back after a little less than a year. I thought this was impossible at first but the e-mail blatantly said that he was coming back. Then I noticed that unlike how I thought I would be ecstatic I was a little depressed. This e-mail was like the shining beacon signaling the end of my unhappiness but it only seemed to make me more upset. I don't know why but I feel doubting of the whole thing even though it's completely true. The only thing I can think it may be is that perhaps him leaving wasn't why I was unhappy. But I'm not sure and I just want to end the whole thing and keep him where he was before. I just don't think I want him back but I don't know why, therefor I need a little help on why that might be so.