I am very angry but am not sure how far I should go in fighting this guy?

We haven't evicted in CO since we just bought a couple months ago, but I can give you our (limited) experience in CA and AZ:Orange County CA: 3 months (the tenant at first tried to fight it, so that added some time. 

That and evictions, it seems like former owners are getting better at fighting us.  

Also with a vacant building no jobs impacts to the  economy.This is generally an easier sell than you want to build on beautiful and open natural wooded areas where you will get fights from the tree huggers and community at large. 

Is fighting to be financed worth the headache or should I just hold off for 6 more months until I have two years of this job history--even though I will not have two years of tax returns with it?  

Cannot get loan from someone fighting you on terms.  

The dog was smart to sty away, critters will run from humans, usually, but may fight other animals when cornered and any dog can be bitten, so you just avoided a vet bill and a period of observation.

My Clients are often in route to foreclosure and I am spending months fighting for an approval for that Buyer.

And now instead of a cooperative tenant who would have left on time, you have a fight on your hands.I haven't been a tenant in 20 years, but I can still understand the thought process.

Because of the extra hoops needed to to fight through this protection many frivolous lawsuits will die before ever really starting...but it seems like this isn't the answer you're looking for.