I gave my ex lots of love then set her life on fire, but it was for her own good.
I'm not sure I understand. Do you mean metaphorically?
Yes. I knew we weren't meant to be together.
Even if you no longer care or love this person, you need to let them go without hurting them physically or emotionally. Show them how much you used to care by letting them go gently.
No, I had to do it this way.
I don't think there was any reason to be so harsh to your ex. You could have done it in a nicer way, that wouldn't have caused her so much dismay.