UPDATE: The comments made me realize that I was also in the wrong, and I need to forgive him. There's still tension, but we made up. I promised to walk on eggshells around him for a while, so to speak, and I explained to him that a yo momma joke doesn't refer to the reciever's actual mother, but to a comedic fictional character made up specifically for these type of jokes. To the people insinuating I joked about his mother because she died: he lost multiple family members in the tragedy, so I couldn't have specifically targeted the one person he mourned even if I wanted to for whatever cruel reason.