Rights of wife in Special Marriage Act

I m a Christian having married a Hindu 17 years ago. Bore two children, son 15+ and a daughter 7+. I have been living alone with my children from 16 years and serving in a govt scul, children being born and brought up by me. My husband came once a month, residing almost 300 kms away from us, or so. He is also a govt servant. We both are in same grade. Till date I was taking care of all of our expenses. From past few years I was suspecting extra marital affair. I got few clues. A pack of bindis, mangalsutra and a pack of condom which none do I use. In his car dickie. Then a topper once too. I even got his call records. From his own number he has made quite many calls to a lady. Then he has a sim on her name which my husband is using and tthousands of calls interactions between them. He sometimes beat me and children also. Now I cannot continue like this. Kindly guide on my children's issue, their maintenance, divorce, etc. This is not the first time he has proved infidelity but he had an affair with a student of his and also a girl staying close to his workplace.