My Ex boyfriend is mad that I didn't give our son his last name.

My ex-boyfriend & I broke up when I was 3 months pregnant. During the pregnancy I informed the ex that I was giving our son my last name. He was extremely upset. I was alone virtually the entire pregnancy with an occasional text asking how I was doing and 3-4 bootie calls, which I allowed to hapen because I missed him. When I was in labor I called my ex to come to the hospital. He showed up at the hospital, asked me if I was still going to give our son my last name & when I replied that I was he left the hospital and didn't return. He text several days later to see how our newborn was doing. Our son is now 1 1/2 and he see's him for one overnight visit every other weekend and he pays support each week. My question is: Was I wrong in not giving him his Dad's last name?