I had a friend pass away around 4 years ago from a heroin overdose. Initially we were told that it was pneumonia, but then someone finally told me the truth. He had been in rehab not too long prior. He lost his license, which made him extremely depressed since he LOVED his car and to drive, and his job involved driving (I think he worked as a parts guy for Toyota). They accomodated him by giving him an administrative job, but it wasn't the same. He fell into the wrong crowd (He had my crowd and this other crowd). It was hard for us to hang out with him, and I felt guilty, because he didn't live far away, but it did get annoying after some time. If I could go back, I'd hang out with him every day and pick him up. He was a great friend and person overall.
I actually responded to the call, but luckily our ambulance ran right off of the bat so they deferred me to a different station as back-up in case another call came out. On the way back from the station I saw that the ambulance was on his road and dwelled further down and saw it was at his house. I went to the door and was met by his Uncle, who was upset and emotional and yelled at me asking who I was. We didn't hang out at his house often, but I told him I was an FD member and a close friend and asked what had happened. He then told me that Kevin had passed away and gave me a large hug. I then talked to a cop that asked if I knew anything about the drugs, to which I didn't.
He is gone too soon, that's for sure. I miss him immensely. I keep his funeral card in my car at all times for protection while I drive. At first I had dreams about him, being happy and stuff, and on occassion I'll dream about him and others that I knew that have passed.
You just need to cope with it head on, talk to a therapist and the surrounding friends in the group. It's a tragic loss, but you must move on, but never forget.