Michael Mcgraw, Alias: Michael Mcgraw Postal Money Order SCAM! (looks totally legit!!!) Streams Sodus Michigan

My name is Crystal and I am a currently unemployed, but will soon be re-starting community college as a junior.  I will try to keep this to a minimum.  I lost my appartment around 09/25/2013.  I gave my house and mail keys to a neighbor who has seemed to be trustworthy thus far.  I leave the area for about 3 months then I return and reside in Portland.  Well, when I recieved my account summary from the appartment company there was a list of things I owed for, including the mail key deposit. 

So, I contacted the neighbor with whom I left the keys and he stated he returned both sets of keys.  A couple days later he wants to meet up.  When we meet up, he tells me how he has been holding a piece of mail for me this whole time (but had no other mail for me whatsoever).  He pulls out this USPS Money Order.  It was written out to me with my address, and sent by a "Michael Mcgraw" at 32 River Rd Meadow Streams Sodus, MI 49126. 

I don't know the name or why anyone would have been sending me a money order, especially one for $920.50.  It had watermarks and the other fancy security markings and looked totally legit.  Me being the poor student (although that's not a suffencient enough of an excuse) went to a 'Western Union to cash it.  'Took it in, he took it to the back, then came back, asked me a couple questions then informed me that the money order was fraudulent. 

I set myself up for that one, possibly, but I am just not 100% convinced that it was my neighbor.  I don't know if he has the resources it would take to pull off something as authentic looking as this was.  He is not computer literate whatsoever.  Either way, I would really appreciate some feedback.  I had nothing to do with this and I'm very confused as to how I got drug into a scam such as this.  How did they get my address?  Will I get in trouble?  Just not used to dealing with this kind of stuff....  Thank You!