1) i have felt like you! but only briefly; i can't imagine how hard it must be trying to deal with those feelings constantly. i went back to work, then back to being a mom, then back to school (full time) trying to satisfy something in myself by following the advice of others... but after trying all the different lifestyles and serious soul-searching on my part... i've found that being a full-time mom is just where i fit. i *love* being home with my son. but we all have our niches.
2) i'm going to be honest: your husband sounds like a huge part of the problem. you two really need to reconnect. at this point, after just what you've told us of him, i really think it would be in your best interest to *not* leave the kids with him. i think it might help you to go back to work, or try to find something that removes you from the home most of the day. that would also help you become more self-sufficient, plus give you more firm footing when dealing with your husband (as in, "look, we're *both* working outside the home, you need to help out more.")
3) toxic art chemicals should really not be holding you back from doing what makes you happy. there are plenty of non-toxic art supplies out there, as well as a ton of recipes and guidebooks out there for making your own. i've made finger paint before from cornstarch, water, salt and food coloring. absolutely non-toxic (edible, but it doesn't taste good... although for awhile my son loved eating it :LOL), and it worked *perfectly* as paint. there are also a lot of home-made playdough recipes out there made from flour, water, salt, oil and koolaid/coloring that are also just fine to eat. i've also found that personally, other "home" arts can be just as satisfying as "art" arts. i.e., breadmaking, baking, sewing, etc. it fulfills the need to create while fitting in nicely with homemaking.
that's all i can think of right now.
i really hope everything works out for you. i'm glad you can be so honest with yourself.
fwiw, one of my sisters did leave her 3 daughters and her husband to go pursue her dream of becoming an actress / movie star. she succeeded -- that is, she accomplished her dream -- but at the expense of losing all of her family and friends. it is not a path i would advise anyone to take.