There is a saying, "it's not the mistake that is a problem, it's the cover up." In an attempt to conceal a refusal, they are now facing a 2 yr ban and the lawyer gets paid either way.
A TRP (temporary resident permit) could be one option; however, the OP's husband needs to demonstrate a compelling reason to be in Canada. Examples of compelling reasons are: you are a suitable organ donor for your relative and need to be in Canada in order for the organ to be harvested; or you have a medical condition and the best treatment(therapeutic wise and money wise) is only possible in Canada, etc.
Wanting to be a part of your child's life(or with your wife) while noble, is not sufficient to overcome this burden. Reason being the OP and her child can travel to Sri Lanka, or the OP, child and husband can live in another country and the child will still have her parents with her.
That said, the OP is still free to apply for it and see how it goes. I wish her well.