Sorry just need to rant: My dad hasn’t really been in my life since I was...

Sorry just need to rant: My dad hasn’t really been in my life since I was 9 years old, and has lived on and off in Australia. My sister grew up in the same house as me but still had a very close relationship with my dad and saw him all the time and is “daddy’s little girl” and now lives with him in Australia. In July this year we were messaging each other and out of the blue she asked me if my uncle on my dads family was invited to my wedding (my uncle is very rude to my H2B and as a child was emotionally abusive to me and my brother), so I told her the truth and said no I hadn’t which my Dad already knew about as both me and my mum had told him on a number of occasions. The next day my dad sent my mum a threatening message basically saying that he would not be coming if I didn’t invite him and that none of his family where happy with me. So we stood our ground and still said this person wasn’t invited even though he knew that from very early on and had no issue with it. Bare in mind I had invited all the rest of his family even though they haven’t had anything to do with me since I was 9. After a number of aggressive nasty abusive messages from my sister (who my family call the “drama queen”) which I did not reply to as I didn’t want to stoop to her level she then sent more to my mum basically telling her any secrets as sister that we had and also a load of lies about my character to try and tarnish mine and mums relationship. When we first announced we were getting married the first thing my sister said was well me and my husband are going to try for a baby so I may be pregnant. She didn’t say congratulation she or even ask me when it was going to be, so the reason behind her abuse is because she knew that because my dad wasn’t coming she had to side with him and not come as well meaning she couldn’t be fussed around by my family if she was pregnant. I know this all sounds petty and childish but my sister has all through my life tried to one up me or if something good has happened to me she’s tried to make it about her. All my dads side of the family are now not coming either because they don’t like being seen as picking my side. As I have very ill health being and epileptic and suffering from mental health problems all of this has made me very ill and most days not even able to leave the house. I’m now really struggling with the fact I know my sister and myself will never speak to each other again and that I will look back on this period of time which is suppose to be the happiest moment in a girls life and all I will think about is what they have done.