First I would tell the "boyfriend" that he was not eligible to claim the child and that you will turn him into the IRS for filing a fraudulent return if he doesn't immediately amend the incorrect returns ... the fines/penalties/interest for claiming a child incorrectly are severe.
Next, I would explain this to the mother and request that she waive the exemption to you by signing a form 8332 for every tax year you are eligible to get the child so you can go back and amend the prior years and claim the child in the future. This will ONLY get you the dependency exemption and the Child Tax Credit since you are NOT the custodial parent ( where the child lives more than 1/2 the year). The right to use the child for Head of Household status, the Earned Income Credit and the Day Care Credit always remains with the custodial parent EVEN if they do not or cannot file a return.
