The best way to avoid leaking memory is to not allocate any in the first place. Why are you allocating memory inside a "bigint" class?
I was allocating it because my bigints were variable length. IE: I was resizing the container as they grow and shrink.

Theres a lot of copying going on when it keeps growing and shrinking all the time; I only figured out how to do it one int block at a time. So I was thinking that I may change it to only get bigger when necessary, and not bother shrinking it down to fit. A static array should be less of a headache tho, if I have too many problems with variable size ones then I will try that.