I don't want my bf to get into a fight with my ex
What makes you think that they are going to fight?
I am not sure they will, but I just want to prevent things from ever getting ugly.
It's reasonable that you would want to avoid conflict between the two people you care for. Have you thought about talking to your current partner about this issue?
I tried talking to him but he can be a real stubborn asshole sometimes. However, I'm prepared for any outcome.
Are you sure that you are ready for any outcome? I totally understand why you would want to avoid conflict between the two of them, so maybe try talking to your bf again.