I'll try to keep this brief.
I have suffered from depression for years and years, but it has got much worse in the last 3 or 4 years, plus I don't think I left PND behind. DD is 6 now. I finally gathered the courage to go to GP, am considering taking the ADs prescribed and am waiting for counselling.
Now, a huge part of the depression worsening is my relationship with my sister. The best way to describe her is as a textbook narcissist. She has form for cutting herself off from people and getting everybody else to follow her like sheep and ostracise the people in question. It is extremely hard to reason with her. I have walked on eggshells for too long to stay in touch with my DNs and so DD can have a relationship with her only cousins. We live abroad, all my spare money and my holidays are spent visiting them and my parents, often without DH as we can't afford the travel every time. We are the ones always doing the running after them.
Last Xmas' visit was terrible. I spent a whole week crying and decided enough is enough. I would be heartbroken if DD and I were not to see DNs again if their parents don't make the effort to come to see us (which I doubt they will, as I am sure DSis would love it if they had no contact with me). But I cannot waste my life like this anymore. So with a heavy heart I came back home having decided once and for all to concentrate on MY family - DH and DD - and seriously look after myself. This floored me for a few weeks but I was finally coming to terms with the fact that being around my DSis, or even thinking about the stuff she does, does me no good. Contact would be kept to a minimum from now on.
We decided to go on holiday just the 3 of us as a family. This would be the 3rd time in all of DD's life. We've had 5 and 6 days away in the UK in over 6 years. We cannot afford anything exotic but there is somewhere abroad we always wanted to visit in package-holiday land, so the three of us got all excited about it and were just about to book for one week this Easter. It's just a holiday but it made me feel like I was starting to get back on track.
About a week ago I found out BIL is seriously ill. He has cancer, and not a very easily treatable type, which has been a huge shock to us all. It's early days and he's just started treatment. We have offered to help any way we can, although being abroad and practically estranged from DSis I don't know how much we can do, sadly.
So if you have got to the end of this, would you cancel the holiday and go abroad again to visit DSis & BIL instead? Or would you go ahead with the plan and go on holiday? (and obviously cancel at the last minute if things took a turn for the worse 
)