Hello & Welcome, Jack009. I suspect it is not possible to separate the feelings of guilt from depression, PTSD and the legacy of abuse. You'll probably have to deal with everything altogether. And you are doing that with the group counselling and meds. This is probably going to require some time.

Will the group counselling permit you to address your particular powerful guilt feelings?

Please make yourself at home here.

For reference:
Post-traumatic Stress forum
Survivors of Abuse forum