Hi N.,
You are kind of stuck in a tough situation, aren't you? It's too bada there aren't some groups around where you could go as a couple to do things with other parents of autistic kids. We have a couple of friends who have 3 autistic sons. The oldest is now 17 and he has a job doing dishes at a local restaurant. He helps take the offering at church. And he knows EVERYONE's birthday. I kid you not. EVERYONE's, right down to the year. And he makes hand-made birthday cards and mails them to everyone in our church, just in time for their birthdays. It is so cool. Yes, he's autistic. No, he doesn't really interact with people much, except in one=liners that there are specific responses you are supposed to give -- responses I usually get coached on by his dad. But he's contributing to people's lives, caring for them in little ways here and there.
It IS hard to parent an autistic child, and, like any parenting, it's easier to do as a team. Your husband isn't home all the time like you are, so he hasn't had the same amount of time to deal with the whole thing that you have had. And he's probably tired after work and wants to relax. However, going ANYWHERE with a child, to parties, or whatever, is still an act of babysitting, whether the child is autistic or normal.
On the other hand, you noted you can still be civil to your husband -- that's sad, too. There's a whole lot more to marriage than living together in civility. I would be totally lost without my best friend in my life, and, frankly, I'm not always civil to him. Well, I probably am out loud, but I'm not always civil in my head. But he's a good buy and hardly notices when I'm in a snit. :-) This year he did a lot of Spring hunting, and I was kind of angry inside, because I would set aside his day off for a day we could do things together, and he'd go off hunting. grrr . . but you know what ? I awoke Memorial Day with him having gone MIA. I located him (at 6:45, mind you) in the garden, weeding it for me .. . wow !! I was so shocked, and felt very, very loved.
If there is a way to relight the flame in your marriage, I would vote for that, maybe by you allowing your husband into the mom/son cocoon, and also by him learning to work with his son and share the responsibilities of parenting. You also need to have someone who will babysit (like a parent or relative?) so you can do adult and fun things together, too.
Parenting is a team process in a marriage. As a team, you will both have different ideas of how to do it, and you will both do it differently. The good thing is that you will also have more ideas of how to handle stuff when there's a problem, and you will have each other to cling to and share the burden when times are tough. But it does mean that you won't always agree, and those times can be horrible.
I am hoping you guys can work through this, because this is HIS son, too. If not, definately be civil. But if it doesn't work out, you may still need to help your husband to parent his son. That way he will have better visitation time, and you will get some "time off", which is incredibly important when you're a single mom. Frankly, I've been married, and I've been a single mom. Being a single mom was easier than being married to my ex-husband, but being married to my current spouse is a walk in the park compared to being a single mom. And he's saved my kids a whole lot of trauma because he is a very calm person, and he keeps me calmer than I would otherwise be.
I hope things work out for you guys. Life is hard, and we do get handed challenges that we don't feel up to meeting, but we don't really have the option on them. But there are also some wonderful blessings out there when love wins over the things that divide us.