For me, my first true love seemed impossible to get over when it ended. I felt like a part of me died, but with time and self reflection, I eventually did move on. I assume the reason it's so hard to overcome is because love is an amazing feeling and when you experience it for the first time, we can't imagine it ending because love should last forever. It's hard to get over because we don't want to lose that feeling of love. That's also a reason why many people stay in relationships that aren't healthy. They want to get back to the time where the love was the main part of the relationship.
I know, but it will get better. Trust me. It's all part of life.