My husband just ran off with his new girlfriend three weeks ago, and now he is saying he will claim her two children on his taxes this year. Obviously this is a separate issue that I can handle with the IRS however I want to know how it will affect me when I go to file for our children. I have a son it's almost one, and we lost a daughter at two months they were twins. First of all can I claim my two-month-old, even thought he was only with us for those couple months, and secondly how will it affect me if he files with this other woman, will I lose credits and deductions?