12 year old son's behaviours

Hi I am new here, but am keen to get some advice  / feedback about my son who is 'on the spectrum.' He is 12, very sweet natured and is high functioning - in mainstream school with 25 hours per week support - and clearly has learning difficulties alongisde the ASD, as he has problems accesing the curriculum. He still sucks his thumb when he is at home, (he has the sense not to do this at school). He mostly dislikes school, but tolerates it and has made some connections with other, similar boys. My main issue is that during evening and weekends, he doesn't see why he should leave the house at all, and would much rather stay home (preferably in his pj's and dressing gown) watching TV, playing on the laptop (minecraft) or doing his puzzles. If we have to go out it is a real struggle to get him motivated to get dressed and out of the front door. He will complain and physically lean his body weight onto my husband and I for much of the time whilst we are out. I am uncertain as to whether this is an 'Autism' thing or part of his personality. Does anyone else have similar problems?

Additionally, my husband does not react well to my son. He often shouts and tells him off for sucking his thumb, sometimes slapping him or pushing him around. This upsets me as I am obviously protective over our vulnerable son. My husband calls him lazy and I feel that most interactions between them are negative. These situations often occur in front of my two other (younger) sons, and they will sometimes proceed to join in, (jumping on the band wagon), trying to get my autistic son into trouble with his dad, and so the situation worsens.

I have tried talking to my husband and explaining that our son's condition can lead to this sort of behaviour, etc, but he just says I am criticising him / calling him a bad father. Our son was diagnosed between the ages of 2 and 4 and I feel that maybe husband has never really accepted this, which is why he makes no allowances. Additionally, I do all the school co-ordinating, meetings etc alone and sometimes feel overwhelmed with it all.  I want to help improve their relationship and any tips would be much appreciated. 

Thank you!