PTSD-death of loved one?

I was just curious if it's possible to develop PTSD after the death of a loved one. I had a boyfriend when I was 16 who died in a car accident a year later with his brother who I was also close to. I know everyone responds differently to situations such as this but I developed some pretty weird mental stuff afterwards...I only truly married my husband because he looked like him physically but it turned out he was verbally and mentally abusive. After I had my son I became obsessed with my own death and that of my son, developing what I thought was hypochondria and doctors said I had OCD but none of the treatments for either were working for years....my husband left my son and I a little over two years ago and I have this very intense dissociation to where I can hardly even bond with my own son and it brings me on the verge of suicidal feelings. I know it sounds kind of weird but I'll spend hours just looking at him trying to conjure up my feelings for him but feel nothing...I can hardly take care of myself as pathetic as that sounds, I can't concentrate and have terrible intrusive thoughts. When my son was born I didn't think I could possibly be any happier, I remember looking at him though one day thinking how blessed I was to have him and all of a sudden this intense fear of losing him came over me and I developed intrusive thoughts about not loving him anymore which gave me intense anxiety. I have a hard time even hearing my sons name even though he's still alive and within my reach any time...I worry that this is making him suffer and my own feelings of inadequacy as a mother leave intense feelings of guilt to top it all off, I worry that he can sense my distance and will hate me for it some day. I've been diagnosed with anxiety and trauma but am not currently seeking treatment. I have difficulty finding people I like or trust with my problems, the guilt I have over these thoughts of my son make it hard for me to talk about it with strangers, I think they'll think I'm a piece of **** mother who just doesn't care about her own child and that I'm evil and don't deserve him. I'm going to pay 3500 to have some neuroimaging done on my brain to be properly diagnosed and treated for whatever this and I'm going in this month on the 14th for 3 days in an inpatient clinic, I hope my son never finds out I had to do all this. I feel so isolated from everyone and can't let people in and it feels so lonely. Anyone have any thoughts? Sorry this post was so long but thanks to anyone who took the time to read it. I recently got a hold of my biological father through myspace and according to that side of my family there's no history of schizophrenia or anything..I don't hear voices or hallucinate. I'm the only one on my mom's side with the type of "issues" I have so I don't get it. I'm afraid of bonding with my own son...it doesn't make sense because we used to be so close it breaks my heart and it's pathetic because I'm 25 and shouldn't be having such juvenile feelings like this.