Is this considered as tax fraud?

My husband and I are both Permanent Residents of USA and we have a child of two years who is born in the USA..I suffered a lot of physical and mental abuse from my husband who has a very violent temper. He was arrested and convicted on two occasions for ault and domestic violence. 2 years ago,immediately after my child was born, he made me and my child to travel to our native country, where he deserted me and my child. He came back to the States where he is living and working. He took illegal possession of my pport and green card to prevent me from returning back to the States. For the past two years, he has not been supporting me or the child, however he has been filing taxes under married and jointly. As I have been a housewife for the entire period, I never had to sign any of the filings.He is continuing to file under married even though he has recently about 3 months ago filed for a divorce in my native country. I have complete custody of the child and have been responsible for it since the time of its birth, he has in no way supported us financially.I was recently informed by a friend that what he is doing, filing taxes as married for past two years is considered as tax fraud as we have been separated for 2 years and I have been living in a complete different country with my child for the entire period and he has also filed for a divorce. I would like to know whether this can be considered as tax fraud and needs reporting?please help. Thanks