As I am also going through this, I'll share what my experience has taught me. You can go through counselling and you might be able to salvage the marriage. No matter which way you go, put your kids interests before either parents. If you can't work it out...
#1 GET A LAWYER. Do not take any action that is contrary to their advice. I would talk to council before attempting to move back into the house. Keep a notebook for meetings and have all paperwork where it needs to be ahead of time.
#2 Close joint accounts/cards. The advice about putting money aside is wise; you'll be needing all you can get your hands on. Cancel your winter/spring/summer/fall holidays.
#3 Look at the last few years of bank transactions on joint accounts. Research dissipation of assets if you see any irregularities and highlight these for your lawyer. This can be a huge factor when it comes to division of assets.
#4 If you have any employee assistance programs at work, use it. Your kids might be having a harder time with this than you are. Never forget that they are stuck in the middle of the mess and are looking for answers too.
#5 If you haven't already, GET A LAWYER