Step number one - if you are using the home computer, you MUST erase all signs that you have been here. You might not be safe if your H accidentally stumbles across this site. If you're not sure how to erase the history and then visit some other sites so the history isn't blank, find out.
If he only gives you enough money for groceries, start shopping really frugally and keeping the change. Beans and rice may just "happen" to be on the menu, right?
Do NOT tip your hand - the most dangerous time for an abuser is when you leave. Be nice to him, don't change your behavior. Ask for help from that nearest women's shelter - they may have some way to get you out of there, even though they're far away.
When you leave, it is ESSENTIAL that he doesn't know where you are. This might be a problem, as I don't know if the law enforcement family members might know where the shelter is. Discuss it with the shelter.
Do you have an old friend that H doesn't know? You should nOT go anywhere that he might guess at; the best thing is to go somewhere they couldn't possibly know about. Then get an attorney. Immediately.
Don't discuss it with your kids beforehand. They might accidentally spill the beans, or might be opposed to leaving.