Your gf's past isn't going to be changed or erased by anything you say or do. So why not be a good guy and tolerate her exes?
And being hostile to her exes is only likely to increase, not decrease, the chances she might cheat on you. She'll be justifiably angry with you.
Most Helpful Girl
Ex means finished or to leave.
There is a reason why they are an ex, I wouldn't expect that they still are in communication with each other.
I guess guys feel this way because they knew there once was a time when their girlfriend had strong feelings for this man.
They are afraid that those feelings can be rekindled.
Feeling this way is natural and understandable, it would make anyone feel uncomfortable.
But like you said if someone already has in their mind they are going to cheat, they will.
Being friends with an ex isn't going to determine this.