Your advice is needed

WHAT'S YOUR ADVISE???

Good morning, post for me but pls keep me anonymous.
It's been 6 years since I got married to my husband but I don't ever go through his phone to read his chats becus I completely trust him not to cheat on me. He posted his picture on his wall and a certain woman commented "my sweetest", I was about confronting her immediately but decided to ask my husband who she was and he told me they were classmates in secondary school but the girl is already married. Immediately he told me she's married I removed my mind from it. For sometime I have noticed that my husband is always restless and protecting his phone too. I never knew what was going on until a man added me on Facebook messenger and asked if I am the wife of Kingsley which I told him yes and he said hope I am aware of my husband doings I was surprised the man now told me that my husband has been the one impregnating his wife and that the three kids he has all belongs to my husband and he has also sent his wife away but decided to let me know may be i am not aware and truly I am not aware. I started doing some underground investigations and I found out from my husband's phone chats that he has even rented an apartment for the woman and paid school fees for the children as their father disowned them and he has not even paid my son's school fees yet. I confronted him and he started apologising and told me a lot of things and how the woman lured him into it. My anger is how can he impregnate someone's wife three times and even kept the secret from me. As I am now I don't want to continue with this marriage, this betrayal is seriously hurting me, I will move for divorce and train my child since he already assumed the responsibility of a father and husband to his side woman.
My mother is saying I should remain here as it is one of the things women pass through in marriage but I can't endure this betrayal. I need you all to advise as I am standing on a confused road now.
 I will be reading the comments but pls try to notify me when you post it.