Dad finds it hard to accept that his son is different

Hi i am quite new to this.

My 6 year old son was diagnosed with autism last year june and while at first i found it hard to take in, now i am happier knowing that all those times my son had his meltdowns and developmental delays, i now know the reason. The same does not apply to my son's dad. He has difficulty understanding the concept of autism and is very negative towards our son saying things like i just want my son to be 'normal' and that he can't ever see things getting any better. i feel like i am talking to a brick wall when i try to explain to him that Cameron may be different but he is just as normal as any other child. My son is non verbal and is due to start special school in september and i am extremely proud of how far he has come since his diagnosis last year with alot of help from his previous school and myself. He is a totally different child to what he used to be. He used to scream bloody murder in the middle of a supermarket, days out were a disaster, i lost support from my family because they were scared of him. even to this day i believe they still are. But now Cam is a happy go lucky child that brightens everyones day with his smile. wherever he goes he is making people smile. I just wish his dad was as proud as i am about how much progress our son has made and i don't know what to do or say anymore.