It's all about her

My partner's brother died suddenly just just overr 2 years ago. It was a terrible shock for the whole family especially his widow. I know people grieve in different ways and that there is no time limit but every time the family gather his widow drinks too much and pulls the rest of the family iinto grief. I was sympathetic at first but after my own brother died this year I began to feel a bit angry that my feelings were being ignored and that my grief didnt matter. She is coming to dinner tomight. I know everything will start off fine but after a few drinks it will all start again. I dont want to cause a scene because I am a bit outnumbered by the rest of his family. I wouldn't start maudling over my brother in front of them. I just wish it would stop.

You stated their "coming" to dinner I'm assuming your in control of the dinner table. You also said that it seems like drinking is the problem. Eliminate the problem, switch out alcohol for another drink so she can't get drunk at all and lose control of herself. Get rid of your alcohol temporarily and say your out of alcohol. (wouldn't be lying)