Ugh, so sorry Julia! You do not deserve this. There must be some really ugly blood between him and your dad. Your uncle also does not seem to have a clue what he is talking about, there is pretty much everything wrong with his statements.
Your dad is extremely supportive, loving and caring and do not let anyone tell you any different.
I am sure you could find a few honorary replacement honorary here - I would volunteer as replacement aunt! (given that I am a bit older than your dad, it would work out too). I already have 7 nieces and nephews, the more than merrier :-)
Oh - and I knew you planned SRS but I was not aware it is only 4 weeks away! So happy for you, this is something to focus on and you should not let any negativity affect you :-) You are strong, you are beautiful, kind, with a big heart and a loving immediate family.