Exes Grandma has Leukemia 💔 please help

So my ex grandmother "Nana" just found out that she has leukemia... and I want to go see her, but I don't want to see my ex because my current bf would get upset.

When I was with my ex I feel hard for him, and he just broke it off without any warning, and when I moved on he tried to come back into my life and just made things difficult for me. He broke my heart and I know seeing him would be hard for me.

Should I just suck it up and go see Nana and risk the chance of seeing G. Too or should I just continue to support her by just calling her?

I called her today and she wants to see me... I'm so confused as to what to do... please help...