My family is in denial...

I have a 3 year old boy who was diagnosed with mild to moderate autism. He recently started school and he was placed in a special class. My husband and my in laws do not believe that my son has autism. They say this because my son had a speech delay but his speech improved once he got help. He says a lot of words but he doesn’t fully talk like a 3 year old should. He doesn’t communicate very well with kids , he usually approaches them and then wanders off. When he wants something he either points at it while pushing me towards what he wants or he would say “a cookie” for example. My son also can’t stay sitting down for more than 10 minuets when he plays with his toys unless it’s something that really interest him. He likes to line up build things and line up toys, water bottles, or anything he can find. He likes to build things. Another behavior he has is he is scared of certain sounds or music. When he got evaluated, there was a moment where he was taken to a preschool class next door and he didn’t notice the kids around him, instead he was more focused on the surroundings of the class. Well as soon as one of the teachers put in the clean up song, my son started crying and ran out of the room upset. I was also told my son knows a lot more for a kid his age. He knows all the shapes, ABCs, can count up to 30, and he knows all his colors. I just don’t know what to think or do with all the comments I’m getting from my in laws and husband. They make me feel like it’s my fault my son was diagnosed. Maybe I am a bad mom and every decision I make is always wrong. 😔