Honestly, considering this person had the intent in their mind of harm there was a high probability that even if you chose to speak out against this situation it could have escalated. Sometimes people don't think, they just do. Unfortunately, odds are there are many in this world who spread hate. So if it be any consolation you could do acts of kindness to any foreign individuals (as to pay it forward) . Sure it won't erase the past but at least you can build a bridge and show anyone there is good in people. Since it is clear you do have a kind heart.