Still angry at coworker who betrayed me

I resigned from a high level position a few months ago. My closest coworker and friend, who I got the job for, betrayed me and it was a terrible situation. I am relieved that I am out of the organization, but it was a very tough situation. I’ve been working with a life and well-being coach on self-healing and compassion and creating a narrative that focuses more on the positive and redemption and not powerlessness victim. But, I get very angry at her several times a day. I feel like my anger is literally holding me back from moving forward, even though I am in tangible ways. I guess I’m mainly sad, but it’s also contamination that I don’t feel in control of. Thanks!