Son with special needs

I’ve been told recently that my child may be on the spectrum. We’ve always suspected but it’s never been 100%. Still is not but it’s making more sense as he gets a bit older. At this point, though, he’s behind in school and also very disruptive at home. He displays a lot of anger toward family members when not getting what is wanted, etc. There are tantrums and in general it creates a stressful environment. I have improved so much in how I respond and deal with it and also try to help the sibling to deal with it. My husband, though, is not very involved in knowing what the situation is with him and then gets super frustrated with the behavior. For example, he does not participate in the meetings to discuss progress with school or therapists, so therefore really doesn’t understand the background of why the child acts as he does. Then, when there are outbursts, he says he is spoiled or a brat. In the end, this is causing many issues between us because then the protocol we had previously agreed upon to deal with such issues is not followed [by husband] and there is not a strong foundation, schedule or response to the behaviors for the child (as we are instructed by the therapists). Husband always has excuses for not coming to meetings and I think does not engage becuase it’s a hard pill to swallow but it’s not serving our family with him not being informed. I have spoken to him and his response is defensive. Any suggestions for thoughts to better deal with the situation?