Mmm, I believe it’s called survivor guilt - ‘if they did, why didn’t I?’ Or worse, ‘I should have died rather than them’. Of course, the latter doesn’t work at all, you can’t make those sort of trades, even for those you love and need the most. And two people dying, rather than one, hardly helps either. Pause and consider - would the person you lost want you to die? Even in sympathy and love? Highly unlikely. They would want for you what they doubtless wanted for themselves - to get better, to live. You can do them honour by doing your very best to live up to that hope yourself. Be sad at this time, grieve but don’t feel guilty. Mortality is hard to deal with - at least at first. It’s one of cancer’s many gifts. But coming to terms with your own mortality can be a real gift, in the scheme of things. Best wishes.