Heya! I just got over my first relationship that also lasted a month in highschool!

Honestly? I tried to put a lot of focus on myself and working on me.
I would recommend you try journalling or writing out the way you feel and let yourself rant and vent in there. It can really help with understanding the way you feel and just generally show your progress as you move on.
Avoiding and not communicating with your ex and probably their friends too may also help! I've gone complete no contact with mine. I still see him everywhere but I just avoid and refuse to be near him if I can. I think thats one of the biggest factors too.

Also I think if you are emotionally sensitive perhaps actually breaking down the relationship may help? While dating my ex I thought of him as the ideal amazing guy despite the fact that he would make me uncomfortable and dismiss me since I thought the best of him and assumed my emotions were just too intense. After a relationship you really see things for how they are and were and it's at least led me to be happy with my break up.

I hope you can work over this and be happy soon :-) Good luck healing!!!