Your ex-friend sounds toxic, and will likely have a miserable life because of their own personality. People often essentially curse themselves by not being an aware or noble person.
It has been said, that the best revenge on someone else is by improving yourself. But if you feel you must do something, then try directing gray-red energy into their skin to cause bad acne and other skin problems.
You can heal from the damage they caused to you. Detach links to that person, and focus on yourself, self-care, appreciating yourself. Rose quartz can help with this.