We all need some kind of support and lessens the feeling of being isolated when you know other people have been in the same situation. If you do decide to leave without his prior knowledge please be prepared, you might not be able to go back for forgotten things, as is my case.
I totally agree with everything TBagpuss advised. I had a joint bank account, I tried to withdraw a substantial amount without his knowledge prior to my leaving but was unable to do so because he would have found out my intentions. I did withdraw a small amount & used the joint credit card for items without raising suspicion. Remember important items like passport, birth certificate etc (i left my marriage certificate behind because of bitter thoughts of my marriage which I later regretted as you need this for your divorce petition)
Once I made my decision to leave I planned my exit carefully, I only took items of clothing etc which I really needed or wanted - therefore he didn''t even realise what was happening.
Good luck in your decisions - hope all goes well - like I said previously I have never regretted what I did, have never felt happier in all my life and feel free to be my own person which is great!