Is one of my friends anti-Semitic? How would you confront this issue?

You said in your first sentence that it was a friend, friends don't have to agree on everything. I disagree strongly with several issues with my own brothers & sisters but we don't argue each other's interpretation of events and such. It's hard to gain back a brother or sister you have offended. I will say my belief and they heard me and I heard them, if both want to elaborate that's fine but there comes a point you are wasting time and going no where. Focus on what you can build together.