A very good friend of mine who was in a situation very similar to yours followed this plan. She got it from her sister who was also in a bad situation, had had enough and was finally ready to take action so she could start her new life.
It is direct, vicious and leaves no room for pleading or declarations of
"But, I still love you."
You will need some prep-time, about two weeks, a well organized, written plan of attack and at least 2 well trusted family members and/or friends to pull this off.
What you will need.
A good nasty, divorce lawyer.
Get a real scumbag who is in it completely for the money. They tend to know all the nastiest tricks and have no compunction about fighting dirty in case things get ugly and you don't have the balls to go after his.
If the thorn-in-your-side will not cooperate in finding his own lawyer to start things, then you get the jump and file first. Nothing says "Go Away A-Hole!" like being served a summons for divorce.
Get a very large storage unit, paid in full for at least one year, under a friends name.
A locksmith
A "for sale" sign.
A large box of condoms.
The Prep Work
Withdraw all funds out of any and all bank accounts. Have the bank convert everything into bank checks and give them to your most trusted friend or family member to deposit into an account with thier name on it. You can be a secondary name on the account so you can get a debit card to have access to money.
Have your job re-route your pay checks via direct deposit to new accounts.
Cut off all credit cards, yours and his. You can also alert all the credit card companies not to let him apply for new joint ones with both your names. Tell them you are now legally separated and will not be responsible for or pay any accounts that have his name attached to them.
Take out an ad in a local paper announcing your separation both marital and financial. Renounce yourself responsible for any and all debit incurred by your near-ex forthwith.
Check your credit reports at least every week for the next few years. Be aware of any new open accounts that you didn't apply for.
Get a pre-paid cell phone. Give the number out only to those closest and most trusted and don't let your soon-to-be ex find it.
The Plan
Get your unwanted room mate out of the house. If he is a sports fan, get him tickets to a local game featuring his favorite team. Get two tickets so he can take a friend. If one of his friends is sympathetic to your plight and on your side have him call your ex and invite him out with the boys to go to a stip bar...etc... Just do anything that will get him out of the house for at least 8 hours.
Now, for the fun part.
Hire a moving company that comes in and packs up everything up for you.
If something is legitimately his or you don't want it any longer like his favorite tv chair or high school football trophy, then don't touch them, but do leave a mattress in the middle of either your old bedroom where your marital bed used to be, or the living room.
Take everything else.
Have the movers deposit everything in storage unit under friends name.
Call in the locksmith.
Change all locks and also call in a home security company to wire up the house. Make sure the password is something your ex will never think of in a million years. If he tries to break in while you are not there, the police will come by and invite him over to the station house for tea.
Place "For Sale" sign on front lawn.
Use new cell phone to co-ordinate your plan with your accomplises.
Next....have him served divorce summons wherever it was you sent him. That way it will be public with plenty of witnesses.
When he gets home to his now empty former residence leave the front door open.
What he should find is you, naked with at least two other naked men in the act of coitus. For dramatic effect, strew many open condoms wrappers on the floor leading to the mattress you left in the middle of the room.
Have the newspaper next to the bed opened up to both the real estate and the help wanted sections. Both should have several selections clearly circled in red marker.
When your ex finally is able to say something without spurts of foam flying from his lips just smile point to the newspaper and tell him you found several job opportunities he should check out right away and a new place to live.
Tell him you packed up all his trophies and collectibles. His tv chair is on the lawn next to the "for sale" sign.
And last, but never least....you parting words.
"Oh, and be a dear, please don't let the door hit you in the ass on your way out."
I know this is extreme, but it is also VERY effective.
Hey, it worked for my friend.
From what you describe you are never going to get rid of this guy thru the usual diplomatic channels.