Wow this sounds familiar. We had two dogs instead. I understand the anxiety you're feeling as far as how entangled your lives are.
You've gotten a lot of great advice about legal aid, etc. And how to proceed with divorce, but here is what I can offer: get out now, or start saving to do it soon.
Separation doesn't require anything more than a new address, and for me personally, was the first and most important in a string of refreshing and empowering steps to independence. It reduces the chance of you losing your conviction while you start to climb up the mountain of paperwork that is even an amicable divorce and states clearly that this relationship is over. It gives you a safe space away from him. I don't know what your divorce laws are like in your area, but here, being separated for a year prior to filing our official paperwork actually made the process significantly easier because we did not have to disclose much information (no reliving painful memories or officially calling either of us out for the adultery that resulted from our tumultuous time together) and could file on grounds of "marriage breakdown as proven by 1 yr separation". I was able to file without him and only had to send a process server to his house to have things signed. Even though our separation was incredibly ugly, our divorce was uncontested and flew smoothly and cheaply through the court system because by that point, he was as done with it as I had been.
You may want to get a separation agreement at this point if he is vindictive by nature. If you do find some legal assistance, they can help you with this but don't be afraid to read up about it on your own too. The amount of information available to the public on this stuff is amazing because there are plenty of people just like you and me who couldn't afford the retainer on someone to do it for us.
It helps, too, to realize that living without him isn't as bad or even remotely as difficult as you think it will be. Your friends will be more supportive than you think, or they might prove themselves as no friends at all, but the chips fall where they will and it will be okay.
You will be okay.