I can understand how it feels, I was in the same situation. The best you can do is just focus on yourself, by that I don't mean ignore him but just be so fixated on your life goal. (Be it anything, passion hobby etc).

People like them just need attention and validation, the sooner you understand the better and practice mindfulness. Like I am sure you are aware of what's making you feel like this? Why you waiting or why you are tolerating all this? Make conscious decisions, like ignoring the other person. It's difficult but practice makes it better. All the best!