I am afraid that i have black mold on my fridge...eating something with mold can cause me severe harm like brain damage? can i change as a person?

Unlikely: In general, one should avoid eating spoiled food. On the other hand, it will take a massive dose of molds( 10,000 or more x) to even potentially for mycotoxin to cause any damage. If you have any symptoms, they are more likely from something else in the spoiled foods and not from the molds.

Unlikely: Te actual toxicity of any mold can be looked on a 2 main forms. An allergic response, as you can to pollen or a toxicity from chemicals created by the mold. Most dark molds are not the Stachybotrys species that makes toxins. These live in places where there is moisture & nutrients like cellulose (wallboard). It is doubtful that any refrigerator could support their growth.