Hmmm, I'm a little similar to you
I think its pretty terrible that ur hubby would try and stop u doing something u want to do. My fiance is fine with me going to church, as long as i dont try and make him go (he went to a catholic highschool...bad memories for him) and it makes me sad that he doesnt want to go, that i cant really share things with him, but im glad he doesnt make an issue of me going.
But, did u hide the fact that the kids were going to sunday school? thats not good either. I lied to my fiance a little bit. The first few times i went to church, i didnt tell him, so that when i did tell him i was going to start going to church, he didnt need to be worried that things would 'change', that i would become a weirdo or anything, coz id already been going. i removed the fear, in a way.
I'm not sure what your husbands issue with church is, but maybe the best thing you can do, is start being honest. Unyoked or not, no marriage works on lies. Tell him you want to go to church and ask him that he gives as much respect to your wanting to be christian and go to church as you will give to his NOT wanting to go to church.
Resist preaching, your best witness for God is your life. Dont nag, make him feel guilty, beg or other to make him go to church. Remember, God, in all his mighty glory, gave ur husband free will, so u must do the same. Dont give him a reason to resent God/church, but slowly show him the way to make ur life mean something.
Sunday school is good for children. It teaches good moral lessons, the kind every parent believes in, religious or not, and also many bible stories etc that are referenced everyday in secular life. eg/christmas, the golden rule, the 10 commandments, adam and eve, noahs ark, turning the other cheek, a judas, horsemen of the apocalypse, an eye for an eye, Goliath, easter, wisdom of king solomon, the Lords prayer, Love is patient and kind....., Valley of the shadow of death [psalm 23]etc. A basic grounding in the bible is a good thing, our society is based on christianity, our laws first came from the bible, high school literature class is full of biblical allusions, reference to things in the bible.
Hopefully, ur husband will see that God works miracles in ur life, that church makes u happy, and that he doesnt 'lose' you to God, nor do you become brainwashed. But please, dont be secretive anymore.