Hello LW. Sounds like you are having a hard time. Lots of people out here are wishing you well though.
From reading the posts here, you are not the only one to go through such a horrible experience. However, when it is happening to you, it is no consolation, is it? I remember feeling very alone one night, and the idea that hundreds of thousands of couples were going through a similar thing... well it just made me feel more miserable.
However, once I had physically separated from the X, life just got better and better - so hold on in there.
Regarding your selling the house before or shortly after your H moves out, I think he is being a tad unrealistic & naive. Either that or he realises that you have the right to stay there with the kids until they reach the age of majority - he may well be s**tting himself at having what he no doubt sees as "his" money tied up in the property for the foreseeable future.
Do get legal advice. And do ask your solicitor to act quickly - they can be very slow at times. Be careful though if you get into the habit of e-mail correspondence with them - they will still charge you a silly amount for reading your e-mails. To keep costs down, keep all contact with them short and to the point - make notes of what you need to ask in advance and read up as much as possible yourself. I know I sound really cold-hearted about this, but with a partner who is a game-player and manipulative, you have to get organised and be very business like when it comes to your divorce.
Disregard his cr*p comments about you making the final decision to leave - at the end of the day, you have stuck it out for a very long time, willing his behaviour to improve and trying to keep it all together for your kids and family (and for yourself too - it sounds like you really did care for him originally - and no one sets out to have a divorce ).
The reason you are leaving is because you can't go on living on egg shells and negating your own personality without risking your mental health. And you don't want your kids to grow up believing that it is normal for adults to throw temper tantrums, use coercion, etc.
Don't feel guilty about what is happening. I personally don't believe that it is healthy to cast yourself as a victim - but you have been wronged in this. By breaking out of the situation though you are being strong and taking control of your destiny. Lots of people on MN admire that. Keep strong .