Extra marital affair of husband

Dear Sir, I was married in 2002. It was 15 years now and my son is of 14 years studying in 9th std. My married life was not good since starting. First, there was a financial, family & other issues but now I get to know that he is in extra marital affair with his colleague teacher. He is running play way school. First time my son had seen Condomn in his school drawers then he saw his father with his colleague teacher so many times. Even once he found used condomn in his pocket. This was more than one year when he had seen all this things in some time interval but I believe my husband too much that he can't do this. I ignored all the things and even I tried to convince my son also that there was nothing like that about his father because my husband was Amritdhari and shows himself as very religious man. Six months back I had seen some whats app message which was clarifying his relationship. I tried to discuss with him and he said there is nothing like this. It's one of his friend joking. Then again I got some more evidence. Then he started opening his relationship and now finally he has confirmed that he is in mentally & sexual relationship with other women. I don't know what to do. I have his audio recordings with other women and even his confess in front of me but he was blaming me for all this and was saying that he can't leave that lady like this. Please suggest the ways to come out of this situation. My son is in 9th std. and he knows his father relationship but it was very difficult for him to leave him in this stage. Now, am also thinking to leave him as he was emotionally killing me each and everyday. He always check my phone, record my talks with my Mom so that he get to know my financials.