I feel that it completely depends on a lot of factors:
- what kind of relationship you had
- how long you were together
- how amicable the break-up was
- were you friends before?
I am still friends with almost all of my exes, bar one. That relationship, however, was a toxic relationship.
Some exes and I are still very good friends and can chat about everything, including our current partners without a problem or any jealousy. Others we still chat and meet up for drinks but we are different people.
I do believe you can be friends with your first love, if it ends well and you've broken up because you grew apart.