I can't speak from personal experience regarding marriage as I am still single but I imagine it would be very stressful to have lost someone that was close to you as it approached such a significant event.
I can guess it would have taken a lot of emotional strength when grieving your grandmother still on that day.
In therapy I am often told I need to be more nice to myself and maybe it's applicable here. Heaps and heaps of gentleness is warranted because we generally do the best that we can with our circumstances.
I also feel isolated at this point and want more support from my family than I receive it is not an easy situation but I just do everything I can to ensure I feel okay every day.
If people in your life aren't good and supportive maybe just take some space and be there for YOU first and foremost so that you are your own "loving" best friend and support.
I hope you feel better if not now but in the near future.
