Focusing on me

I’m dealing with betrayal in my marriage which has gotten me to The Life Coach School. I was told I need to stop thinking about my husband, stop looking at what he is doing and not doing, I can’t control him and just focus on me. Don’t try to fix the marriage. Fix me and become the best version of me. Yet my thoughts take me to a dark place about exactly what I’m not supposed to do. How do I heal and focus on me with the model? I don’t want him and what he did to haunt me the rest of my life or define me. I want to win and beat this darkness.