Has anyone ever felt like their spouse/significant other AND the person they cheated with deserve punishment?

About 2 years ago my then fiancee had a huge affair and it resulted in him leaving me for her, and leaving our then 4 month old baby with me. Since then I have had anxiety and depression issues. I have though of the girl he cheated with and pictured myself just slapping her repeatedly and yelling at her and cursing at her. Things that would make God ashamed of me. I'm not a vengful person and I would like to say I am fairly forgiving. Toward both of them, I am having a really hard time coming around. I feel like this world would be perfect if she jsut disappeared or died tragically (not that I would do anything to her), if she experienced hurt for the rest of her life and likewise for him. I jsut have so much hate for them both for what happened. I don't feel like either of them should be happy again and I don't feel like either of them could ever pay for their stupidness, or be sorry enough. I want to have empathy and grace for them, none of us are without sin or fault. If God can be merciful on me, I want to be merciful on them. How can I? What is stopping me here? Am I nuts?