Getting an agreement in place takes time. The first thing that I would suggest to you is to not allow yourself to be railroaded into signing anything. My ex had been gone for a year before she got around to seeing a lawyer and us beginning to negotiate a settlement.
An important thing to keep in mind is that even though there are a lot of forms and guidelines, this is essentially a business deal. You can negotiate whatever the heck you want. The courts won't sign off on it if it is too one-sided but that is how I got an acceptable deal in my case.
Since you are on disability and will be caring for your son, you may want to first find a lawyer and then see about getting a temporary support order put in place so that she will cover your expenses. She has an obligation under law to you and to your son.
I used the "Collaborative Law" process here and it worked reasonably well. It's intended to reduce the conflict (and the costs) of getting a separation agreement. As the lower income earner she will probably have to pay you spousal support and she'll certainly have to pay child support. The government website provides a calculator for the guidelines.
A little known quirk in Canadian law is something called "the rule of 65" which you fall under. If your age plus the years married is more than 65 you are entitled to permanent support. Not a lot of people know that.
I would suggest keeping your knowledge and activities quiet and close to your chest. Fully expect her to turn into a monster when she realizes that she can't just prance off into the sunset.
You'll need to assemble together all the information for the financial disclosure. This includes lists of all assets, debts along with a budget of what it will cost to support yourself and your son.
So - start gathering your information, find a lawyer - and don't agree to anything without proper counsel. In fact, under law I believe that it is required that each party to the separation agreement have independent legal counsel.
Good luck. This is going to be tough.
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells