Spread Out the Heat
Almost assuredly what happened was you used chilis that were hotter than you expected. (I am assuming you used fresh chilis somewhere in this process...) I had this happen to me once with a set of New Mexico chilis that were about 3X as hot as I expected, and well, the results were painful.
As stated above, the only way to beat the heat is to spread it out over more product, and here is why:
The thing in peppers we know of as being "hot" is a chemical called capsaicin. In it's pure form, capsaicin is powerful enough to burn through your skin - it is that powerful an irritant. But it is much milder when found in peppers thankfully, but it is that irritating property that we feel in our sensitive mouths that we know of as "heat".
The capsaicin in a pepper is found most strongly in the fleshy tissue inside the pepper that holds the seeds. Most people think it is the seeds that are hot, but in fact, the seeds have ZERO capsaicin in them. If you want to make your peppers that you add to a dish less hot, you have to remove the ribs that are holding the seeds - not just the seeds...
Anyway, so think of your dilemma like this: you have added too much of an ingredient to your chili. In this case, the ingredient is capsaicin. The only way to spread that out is to make more chili so that you have added the right amount. If you started the recipe with twice as much beef as the recipe called for, you would double all the other ingredients following to balance that out. In this case, you have done the same thing, but with capsaicin instead.
Make sense?
And on a personal note, thank you for recognizing that just because the chili is super-hot does not mean it is good. There is a woeful trend occurring in American cuisine with respect to spicy foods where people are equating "hot" to "good". This has never been and will never be the case. So kudos to you for trying to get it right instead of just making it too hot to handle.
