I was curious if doing too much cardio exercise can actually defeat your efforts of losing weight and burning fat. Is there such a thing as doing too much cardio exercise?

Yes there is, but the amount that you can define as "too much" depends on each individual.
On the other hand, the effect is not on burning less fat (you always burn more if you exercise more).
Negative effects are a weakening of our immune system if the exercise is too intense or too prolonged for your particular level of fitness.
Only a trained Fitness Trainer will be able to evaluate your specific level of fitness with more precision, but, as a rule of thumb use 30 min of cardio exercise daily max, if you have an average fitness, and less if you are not used to exercise much (10 to 15 min max).
To avoid negative effects make sure to eat a healthy diet with enough protein and vegetables. They are important to produce the enzymes that will help in the break down of the fat and in the rebuilding of your healthier self.
Good luck with your program, keep at it.

Too much cardio can actually burn muscle rather than fat.. leading to a lower metabolism and often a "skinny fat" appearance.