O + y may be the most expressive two letters I know of. It is a cousin of OMG. “Oy” is an all-occasion response. Here are a few examples of what “oy” might mean:

• How scary that must be! 
• That’s just so sad
• Now that you told me that, I am worried
• I hope they will recover from their accident/illness/job loss/divorce
• I cannot believe he/she did that or said that
• The news is bad (a cancer diagnosis, an approaching hurricane, a son has flunked out of college or the entire heating system needs to be replaced)
• The news is really bad and someone has passed away (Add “vey”)
• You have received some unsettling news in a text and don’t know what to say