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Information you was given is correct - not only dependent care expenses may not be deducted with "married filing separate" filing status - but some other as well.
Please see for reference IRS publication 503 - http://www.irs.gov/pub/irs-pdf/p503.pdf
While the "married filing separate" filing status is the best protection from the situation when your portion of the tax refund would be garnished - other options do exist.