First of all: everything is ok, don't panic, this is a normal ADR.
Before you got married, I assume you had divorced. If you did so in Canada - just provide a divorce certificate (you can get a copy in the court that granted it if you don't have one), if it's from another country - get a certified translation.
Simply create a document with description of your relationship dynamic. How you met, how you became romantic, milestones, proposal, important dates. Imagine we're sitting in a bar and I'm asking you how you met your wife and what happened next - and you're a couple of beers deep and can't stop talking about her and your relationship. Basically do this, but more formal and in writing
The request pretty much sums it up. Check IRCC "proof of contact" description. Take some screenshots from the messengers you use and translate them officially in English (if your native language is not English), demonstrate the dynamics and how you communicate (we literally showed the number of "love you", "hug you" etc sent to each other). If it's in English - you can literally load the entire message backup, I saw people here providing thousands of pages. The concern here is that you don't communicate often and in a romantic way, so just prove them wrong! Also, do you have any social media presence together? Show it as well!
Again, just another letter explaining what they're asking. Look into it from an officer prospective: you got married five years ago, have lived apart and suddenly decided to apply - what if there's no actual relationship anymore, and you're basically helping an ex who is still formally your spouse? Show that it's not the case, explain your plans and thought process behind the decision, show how you maintained your relationship throughout years. Yet again, remember the "bar" scene and imagine you're explaining it to a stranger.
Same as for divorce: just get whatever you have for the divorce process, translate if needed, write explanation about each document or about whatever has happened during the divorce.
I'm sure you can prepare (or at least draft) most of the stuff shortly. Do it, translate whatever needs to be translated, and if you're not sure and the case is more complicated than "we're in genuine relationship and just didn't show it properly" - speak to an immigration lawyer and show what you have.