Many people, including your supervisor, will have negative remarks regarding your research. In some cases, if you’ll have to give a talk at a conference or in front of your research group, professors will crush you with questions. Although it may be hard, you need to take it positively and learn from what all people have to say.
All DBA students have to go through this process so you should not believe that you failed in any way. Listen to all critics, negative and positive feedback and use all of them to improve your research. Sometimes the feedback will sound plain mean, and some will be, but you need to recognize good feedback, tolerate it and try to make the most of it.