Is there any possible documentation that would indicate that the "family business" was co-owned by you? Was there emails addressed to you by him referring to "our" business? Was there joint accounts? Did you have signinging authority? Were you named in documents of incorporation?
These are just examples, try to be imaginitive, I don't know anything about your details, you are the one who is an expert in your own life. You don't have to convince me, you need to be in position to convince a judge and you need paperwork.
Meanwhile, how were you paid? Did you log hours? Did all the money go into a family account? This will make a difference. If you worked and the money went into a family account then it gets complicated and messy, you will need to tally up your hours over the years, determine the worth of your contribution and then make a claim for reimbursment, minus the expenses you would have been reasonably expected to cover. If you got paid by the hour or a weekly salary then it's simpler. In either case you need to tally this and list list list everything that happened. Be organized, be complete and have as much documentation as possible.
Dig out copies of income tax returns, assesments, statement of business activity, etc and make copies. Make copies of monthly balance sheets, bank statements etc. Try to be able to show a money flow for a period of time. If you can just copy the entire 5 years on a computer file, great. If you need to make photocopies and can only do a portion, then be able to show a few consecutive months so you can demonstrate how the business operated. You don't want to run into a situation down the line where he claims he earns next to nothing and you know he earns much more with a lot more assets than he's claiming.
Try to do this discretely without making a big show of it. Right now despite any bitterness and mistrust, you two can hopefully come to an amicable settlement. If he catches on that you are collecting financial data he will get defensive. This is just to back you up, you hopefully won't need it but later when you've moved out will be too late.
Similarly make a file for yourself regarding household expenses, what you paid for, what you put into the house, what then monthly budget was and what your contribution was. Collect copies of property tax bills, utilities, insurance etc. Be able to show what a typical monthly period was like for groceries, etc. If there were repairs or renovations try to find receipts. Maybe you didn't pay and he did, fine. You want to make sure he doesn't exagerate how much he paid.
Start a small file with personal info about the family, ages, SINs, where they go to school etc. You may think you have all the info in your head, great, when you sit in a lawyer's office you save hours of work having organized in a file.
Imagine you are sitting in the lawyer's office now and they are asking you all the details of your life. Save time and do it now, not later when you've moved out and are under even more stress, write out personal details, financial details, dates of important events, costs, assets, how many bank accounts there were, RRSPs, insurance plans, cars, etc etc. List list list. Find as much as you can, make lists lists list and be able to organize it later.
These are things you can do now but probably won't be able to do later when you move out and don't have access to things like bank statements, and also you will find your stress level gradually increasing.
You should get an appointment with a lawyer for a consulation, make a list of questions (maybe things your read here but want them verified) and you should have all this info laid out in a logical order for when you sit down with the lawyer.
