Honestly, I really couldn't tell you how to get through to him. I think the only way he's going to realize that you're serious is if you follow through with what you want to do without his permission. This could really upset him, bad, so it's not very highly recommended. Your therapist should hopefully have a better way of helping you out with how to approach your husband.
Only way I know how to deal with a controlling person (like my dad when I grew up) is to live by the saying "It's better to ask forgiveness than permission." If I wasn't allowed to go to bed, according to him (even though I only had a couple hours 'til my alarm went off for you school) I'd sneak out of the house, go up to my friend's (if he was there) and go to bed. Sure, my dad would be pissed the next day but at least I got to sleep, you know? So, I guess that's what I'm trying to say; do what you need to do for yourself and your child, especially if he's going to have a problem with it, without saying a word.
You know your situation and you know better how your husband will react to stuff like this.
I wish I had better advice on the matter.