So try to realize that, in due course, more rational thinking will prevail and you will come to terms with these negative inner thoughts. When I was told by a well-meaning acquaintance that this would happen, I angrily rejected it. But it is certainly true. I confess to having kept so much on the run that I did not truly confront nor fully accept my loss. I was fiercely protecting myself, keeping a stiff upper lip.
Time is required for such a loss to sink in, for the mind to open to acceptance.
Don't be alarmed if you are hit hard by holidays and anniversary dates. Quite likely you will be busy on the day itself and perhaps not feel very strongly about it. Most of us suffer that experience and probably will, long into the future. In self-defense you will invent your own strategies and devices to get yourself through each day. Some of these you will not feel enthusiastic about doing, but you must force yourself.