I think you touch on the root cause when you made the connection between your emotions being "numbed down" and "feeling like crap." Actually, I think it's more likely that the "crap" we eat -- whether we know it's crap (like processed foods, fast food, empty calories, sugar, etc) or not (SAD, whole grains, legumes, etc.) -- that causes the numbing. We get "hooked" on that stuff, same as we can get hooked on other "substances" that are routinely thought of in negative terms -- like alcohol and nicotine.
Also, like those substances which are often referred to as "drugs," I've learned that it's pretty easy not to understand the nature of addiction until you realize you're suffering from it. As a former smoker, I know that my ability to understand and accept some of the Paleo concepts that so often freak out our "civilian" (ha) family and friends. Only when I finally decided that I didn't want to smoke anymore was I able to stop -- and only when I tried to quit did I realize how addicted I was to nicotine!
Same holds for food. Food addictions are real. I used to joke for years with people -- when they told me they had a sweet tooth, I laughed and said I was lucky to not have one, but that my challenge was what I called a "carb tooth." It's even funnier to me now, having learned what I've learned over the past 6 mos of moving in the Paleo direction -- in that there's no appreciative difference between a "carb tooth" and a "sweet tooth," and, if we want to get even more technical, both of them come down to sugar in the end. The system havoc that's wreaked by over-consumption of carbs and sugar (causing continual insulin spikes and the resultant insulin insensitivity that leads to such conditions as type 2 diabetes and fatty liver) and whole grains (and the gluten that causes inflammation and hinders our digestive system's ability to efficiently provide our bodies with good nutrients) is what causes us to "feel like crap" -- but for most of us, it's how we've eaten our whole lives, so feeling like crap feels normal to us. We walk around not even knowing we're sick until we stop consuming the stuff that keeps us in that state of having reduced energy levels, body awareness, mental sharpness -- you name it!
I believe that the "treat" concept is different for everyone. We all have different limits, and different abilities to resist temptation. If an occasional serving of ice cream keeps you happy, and otherwise on the healthy path, then I think it's part of the path. But if you can't open a pint without eating the entire thing all at once -- and then needing another one tomorrow -- you may want to avoid it. I recently heard someone refer to certain foods as being "red light items" for them -- those things that they know they won't be able to resist. For some people it's pizza, for some it's peanut butter, for some it's Doritos -- whatever they are, keep them out of your house!
On the other hand, the great thing about Paleo living is that you can snack on so many wonderful, tasty and fulfilling things -- avocados, guacamole, sardines, veggies, nuts, etc. And you can eat eggs, and steak, and bacon (in reasonable amounts) -- we don't have any reason to be hungry! Overall, the good so outweighs the occasional craving for pasta or a hot dog that I don't feel like I'm suffering at all.
But if and when you do fall "off the wagon" -- just get back on. There's always room. We always save your seat. Don't beat yourself up -- no shame in saying "whoops" and just getting back on track.