I know you don't know me but I am going to give you a bit of advice. Please don't take it the wrong way because we are all on a similar journey.
It is not just your journey if you are married. It is his also. He may be worried about you. He might be scared as to what is going to happen and needed someone to share concerns with without worrying you. Now I am not defending the fact that he went against your wishes at all. It is all up to us who went want to tell and who we don't. I am just saying that while it may be your journey it is going to affect your husband. It will affect your children if you have any. For good or bad, better or worse he needs to be in this with you.
When i decided to do this, I told everyone. I got the bullshit advice from well meaning friends and the stupid crap like omg I knew a girl who died.
One day we had a gathering of friends and they were all going off about this horror story or that. These were my husband's friends. He stood up in the middle of the room and told everyone to shut up. He said this is her decision and if you cannot be supportive, do not say another damn thing in my house. They clammed up immediately. This was about 6 months ago.
Girl it is totally up to you who you tell.. I guess the point behind that is to see if maybe he is worried or scared. Sometimes, we get caught up in our journey and do not really hear the other person when they say they are worried or scared. Even if he is full on behind you having the surgery he could still be worried about anything going wrong while you are under.
If his parents cant be supportive of you, ignore them. I know that is hard to do but I have had to have frank conversations with my mother in law because of how she treats people in my house. We teach people how to treat us.
Be proud of what you are doing. You made it through pre op and that is fantastic! You will do fine on the band journey. Just love each other and don't spend too much time being angry with him. You are beginning the journey of a lifetime tomorrow. Good luck to you and speedy recovery!