The courts. You have a custody issue.
And you'll have to be clear with your lawyer about whether or not you actually are with your spouse or not.
You realise you started this thread claiming that your spouse was sponsoring you. Now you're clearly claiming something else.
Because what's the truth? Either she's committing immigration fraud (possibly not the first time) by sponsoring you despite the relationship breakdown, or you're lying in hopes of finding some way to get to Canada (presumably to make some argument about separation from your children and staying), also a form of misrepresentation and immigration fraud.
And that's just for starters, there's clearly more going on (like benefit fraud).
Go to a lawyer and stick to the truth, stop spinning your tales here. It'll cost you $$$, and more if you waste their time with transparent fantasy nonsense as you have here. In my experience, lawyers have somewhat more patience for bullshit, as long as they can charge their full hourly rate.