Is it normal to fantasize about revenge on a ex?

Anonymous
Dated a girl for 7 n half years who left me for someone else because I wouldn’t marry her at a drop of a hat. It’s been 2 n half months since then she lead me on I spent about $500 on a fast wedding she wanted but she didn’t show up. We also share kids together that were adopted because of her.. I lost lot of things dating this girl.. she suffers from mental health issues which she refuses to get help for.

Hey mental health issues used to be super bad but I help her get over almost all of them. I feel sick to my stomach I told the new guy who she’s been cheating on him with me 8 days ago zero idea if he’s still with her or not. I am still angry at her made I waste years of my life , made I lost child because of her mad I let her effect my mental health so much when I should have left her the day she was diagnosed with all her mental health illnesses like my family told me too. I still want revenge and hate that I feel this way it’s been 2 n half weeks since I last seen her in person I don’t try messaging her anymore
Is it normal to fantasize about revenge on a ex?
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