This experience took place because the two individuals were a perfect fit for one another’s karma, meaning that even though there was not a past history for the two together personally, each had undergone previous lifetimes with a sibling close in age of the same gender who did battle with them. The roommate, in her set of circumstances, was the bully and your client, in her set of circumstances, was the victim, largely, of a bully. So this was a match of karmic predisposition par excellence to resurrect the dynamics of the prior lifetime living circumstances and its energies of struggle, consternation, blame, and emotional wounding.
The answer is to do further karmic healing and an outreach to that roommate, in particular, would be of great help because the energies continue to linger through a reconnection because of the memories of the events in question. The other way to do a repair would be to do Holographic Memory Resolution sessions for the client and that would allow direct access and healing of the akashic records for the wounding that took place in the current life. Doing both is ideal because the vulnerability leading to this problem is in the other lifetimes so the deeper healing will guard against a reoccurrence of the problem with other humans who may similarly stir the pot.