What works for me is to just put it in it’s place. It’s not something you can ever get rid of, but if you choose to not allow it to bother you, except at a time at your convenience, you just practice. In my own case, I read every self-help book in the popular psychology section I could get my hands on, and found a lot of useful ideas.
I set aside private time, make myself comfortable, and just let all my thoughts wander where they will, and feel all the things that are not convenient to feel any other time. I cry, get mad, feel frustrated, and anything else that happens to be there.
When the alloted time is up (usually an hour), I shower, put on some comfortable clothes, make my favorite desert, and relax before going to bed.
I have made a pledge to myself to be happy every single day for the rest of my life, because I didn’t like the alternative.
After my first husband died, I lived with my family for a couple of years, and they helped me through the “zombie” part of my life.
I took group therapy with a psychologist for six months, after my second husband died, and have done consolutations with a counselor for a couple of weeks on two other occasions. These sessions have proven extremely valuable for me.