First, I'm so sorry about your dad. I lost my 87 year old mom in September in a similar way, very unexpected, she was in good health for her age.
Second - dump this girlfriend YESTERDAY. I am serious. She has just shown you something about her character that cannot be fixed. I know it's a lot to lose her and your dad in the same week but honestly, she's got something pathologic going on. Plus it sounds from the tenor of her responses that it's entirely possible that she slept with some other guy on her binge weekend.Just block her and lose her number. What kind of girlfriend doesn't show up for you when your parent dies and at least TRY to fake some empathy? She's got a critical flaw and there's no way tto debug that program. Over.Period.