So I have a wife and a 12 year old son with severe, classic, nonverbal autism as well as somewhat severe epilepsy.
If you were the kinda father / husband that went out 3x a week with the fellas, poker one night, golf on Saturday, football on Sunday, then that's the precedent your family dynamic has set. So when autism or epilepsy or whatever enters your household don't think your family is looking for you to drop everything, just drop one of them, maybe two on stressful weeks.
2) Readjust your priorities. If you always pictured yourself as the type of dad who was gonna spend the weekends trapped in your garage working on home improvement projects all day, hopefully eventually with your son, you need to let that go. And you need to evaluate is this home improvement project really necessary or am I using this as an escape from my autism kid & my wife.
3) Have roles and jobs in your special needs household that are entirely yours.
4) Have alone time with your special needs kid as much as possible. And during those alone times encourage your wife to go out and take a break as much as possible. And look your killing 2 birds with one stone!