In my very honest opinion, I strongly suggest you forget about the PRRA go back to Mexico and wait out your application processing. Unless you have very strong compelling reasons to prove in PRRA that you are a person that will face severe risks in Mexico with tons of evidence that relate to you (police reports, etc) then you win PRRA. It's a 5% or sometimes less success rate with applicants.
I am not sure how long CIC takes to process the PRRA but with mine it took around 11 months. You should find out properly about your situation and ask CBSA that if you decide not to do the PRRA if you will still be deported from Canada and issued a Certificate of Departure.
Deportation on your immigration application extends the processing because it is required that you apply for Authorization to Return (ARC) to Canada. ARC costs an additional $400 CDN to process with no guarantee that it will be successful. ARC is CIC's formal way of saying you are barred from entering into Canada. A red flag is pulled beside your name in CIC's system. You are pretty much a "criminal" through their eyes once you are deported. However, there are always compelling reasons to have a positive ARC such as your spousal application. But again, you have to show that your relationship is 100% genuine. I would say start having your spouse get you connected on leases, utility bills, joint bank accounts, etc. Things that can show you have adaptability in Canada. It helps a long way for ARC and the spousal part of your application. Know your partner inside-out so you leave a positive impression on your IO at your interview which is a 95% chance that you will have one due to your immigration history in Canada. From my understanding, CHC-MEX is a bit tough with ARC so you NEED TO MAKE A REALLY GOOD FIRST IMPRESSION.
I don't also think that CHC-MEX will make a final decision on your spousal application unless there is a decision made on PRRA. In either way, they will try to eff you over.
Not going through with PRRA stands out better on your ARC application because it shows voluntary departure. Trust me, it will take you a far, far way and the reward will be worth it in the end. Just focus now on building evidence for your spousal application. Maybe your hubby can book a ticket with you when you decide to go back to Mexico.
All of the above is coming from my own personal experience. I was a failed refugee and negative PRRA and got deported from Canada but I knew little about how the system works until I started doing my own research which was very late in the process. I would not wish to see someone else go through what I have experienced with CIC while living in Canada. It was all due to improper communication and hopeless advise from Immigration Consultants and now I am paying for the mistakes the hard way.
Good luck!