Most Helpful Guy
What a terrible situation! I worry too much about other people's feelings so I have a hard time breaking up when far less serious problems happen. My experience is not exactly representative. On the one hand, it seems cruel to add another blow to his life. On the other hand, it doesn't seem like a good idea to stay in the relationship simply because of that.
My suggestion is to postpone the breakup for a while. If you did it immediately after this, there is no way that he could avoid connecting the two traumas. Perhaps you can use the situation to create a bit of distance by supporting him more as a friend than as a boyfriend. For example, if you're not comfortable with physical activity with him, you could suggest that this doesn't feel right under the circumstances. When he gets to the point of wondering why your reactions have changed, you can ease into a breakup. At least then you will have shown support and kindness during the worst of it.