I think it can be done but not on a concious level. My brother died last year and I felt absolutely nothing. I did not mean to shut down but it just happened. I think when something is so painfull it was easier for me to shut down. I was like a zombie for months and in some ways still go back to that state but not as intense. Its not normal not to "feel" anything. Emotions are a release that we need to be able to function. Best wishes.