This is such a hard situation.
I just returned from a funeral, and it reminded me of how many emotions and memories are stirred up; not only of the one that was just lost - but of others that have previously gone before. There IS no other place or atmosphere that is the same as a funeral, so being at one naturally brings back memories of others.
I do think, however, that in choosing to have a vacation in the same spot as you did with your previous wife may not have been the wisest of choices.
It is very important for you to create
NEW memories with your new wife. Memories that have no lingering shadows of your first wife. She needs to feel that she is not in competition with a ghost. That there IS no competition. The heart grows with love, the more you give away - the more you have to give.
If she feels she has your undivided love NOW, then she may not be so threatened by where your body rests once you are gone.
Because in reality, the only thing that will be lying beside your 1st wife's remains are bones and tissue - YOU will not be there. (And neither is your 1st wife.)
The funeral and burial is only for the living, not the dead. It is funny, but I had just written an article on this:
A Funeral So above all else, focus on the living for now. Focus on your wife and that relationship. Possibly have a family meeting with her and your children to discuss why this is such a painful subject - but talk to her first. Your children are adults, although they are your children, your first commitment now is to your wife.