In my work at the university, I see many trauma survivors; releasing guilt is a major focus in treatment. It's often imperative to release guilt to loosen the hold of PTSD symptoms (see below for general definition and description of PTSD symptoms).
Truly, many of us carry guilt about different things that have 
happened in our lives. We often believe that if we had just acted differently that things may have turned out better. "IF I had only taken his keys that night". "IF I had just been a nicer person or a better student, mom and dad would have stayed together". "I never should have gone out with her, I had a bad feeling and I should have trusted myself".
3 basic ways we experience guilt:
1. We feel guilty that we did something that we should not have done, OR we feel guilty that we didn't do something that we should have done. (behaviors)
2. We feel guilty that we thought something that we shouldn't have thought or we feel guilty that we didn't think something that we "should" have thought of. (thoughts)
3. We feel guilty that we felt something we should not have felt or we feel guilty that we did not feel something that we should have felt.(feelings)
Guilt is defined as an uncomfortable or unpleasant feeling that is
usually accompanied by beliefs that we should have thought, felt or
acted differently.
Kubany, a Posttraumatic Stress Disorder (PTSD) clinician and researcher has said that if he only had one hour to work with a trauma survivor (specifically he works with domestic violence trauma survivors) he would spend it on releasing her guilt. He went further and said that if he only had 10 minutes to spend with a victim of DV he would spend it on Hindsight Bias.
Hindsight Bias is basically blaming yourself now for decisions that you made before you knew what you know now. You cannot make a decision back then from the knowledge you hold today (knowing the outcome of the event). But we argue, "no, I had a feeling that something bad might happen". However, this is NOT the same thing as knowing the specific outcome of the traumatic event. You only attained that specific knowledge after the event, and not before. This is an important thing to keep in mind when we are blaming ourselves. We simply can't possibly know then what we know now.
Bottom line: Guilt is a killer. It is
imperative to become aware of what guilt we might be holding onto. PTSD
or no PTSD, guilt can clog up your ability move freely in
relationship(s); to live fresh, clean and free. AND guilt helps no one.
It will only keep you mired in destructive self-harming patterns. You deserve compassion.
"A loving heart is the truest wisdom" ~ Charles Dickens
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3 basic symptom categories of PTSD:
Avoidance symptoms (Numbing, isolation, avoid anything which reminds you of the trauma etc.) Intrusive symptoms (flashbacks, images, intrusive thoughts, or nightmares etc)Hyperarousal
symptoms (always feel keyed up or one edge, looking over shoulder
constantly, great difficulty falling asleep or waking in middle of the
night, easily startled, or anger etc)