Not true, your code does not "become" GPL.
IF you release your code it will be in violation of the GPL and you can: unpublish the release, or switch to a different non-GPL codebase, or reimplement the GPL part, or ask the authors to give you a dispensation or switch your code to GPL.
IF you don't release it and use the code internally you are fine.
It's at least 6 options, only one of which requires licensing your code as GPL.