Try and actively make a separation plan. I done this when I knew I wanted to leave my husband and it really helped keep me focused, and I felt less stressed as I was on top my problems and seeking solutions.
Firstly sort out finances. Are you working? Check the government websites to find out financially what you are entitled to (working or not), when I done this it turned out I was actually financially better off on my own!
Next is housing. Do you have a parent near by that you could stay with temporarily? Submit a form to your local authority to get on the housing list. Also check out private rents in your area, even if it's just a 1 bed flat, anything to get you away from your husband. It may seem financially impossible but trust me, if you feel half as bad as I did when I was leaving, you'll find the funds from somewhere. You don't have to be on benefits to apply for a community care grant, which can help you when starting out on your own.
Now the fun part, plan your life! Make lists of things you want to do, places to go, anything at all just get it all down on paper into your plan. I really think it will help, if anything it will take your mind off how shit you are feeling.