I can still love an ex as a person, regardless if the breakup was bad. I would never wish anything negative on them. It takes more energy to hate them than to wish them well.

This quote means that it is generally better for a person to be kind to their ex-partner, rather than be hateful towards them. Even if the breakup was difficult or painful, it takes more energy (time, emotion, etc.) to be hateful than to wish the other person well. In other words, it can be harder to choose kindness sometimes, but this will usually be better for you in the long run.