Hi Cosima - I know you said no advice but honestly...I think any situation that you feel you can't get through without self medicating is not a healthy situation to be in.
I'm not sure its even necessary?
I understand your grandmother is getting older but that may not mean she';s any less toxic..
I communicated by phone with my family for several years. Even today when I'm back in the fold, I have an answering machine to screen incoming calls because some days I just can't deal with the dramas.
I really believe that's always an option where toxic relatives are concerned.
D