You are in my thoughts and prayers right now, and will be in lots of others as well. It is scary going into surgery and your past experience was freaky for you, so no wonder you are worried.
As for EXBF, well lovie, let's face it, he hasn't been so hot up to now, so why would he suddenly become Mr wonderfully caring, and rush to support you?
Let him go, let him toddle of to reunite with whoever, and go thru the cr*p of pretending what a marvellous and successful man he is to old school pals, who MAY fall for it.
Look into my eyes
and say after me: "all will be well, the surgery will go well, and I will not worry anymore over what he does or doesn't do. I have many friends who care for me and I will be perfectly fine."
And it will be perfectly fine.
God bless