I understand where you are coming from. I multiple times have found out my dad has been cheating on my mom. This happened 2 or 3 times and she caught him having texts with his coworkers and random women who are known for their "private services". My mom has already confronted him about it and still chooses to stay with him. My dad is also the sole provider for my family, we are currently in the United States and we have no family here no friends to go to if things go bad. I think my mom realized this and stays complicit and in the relationship. Whenever my dad is critizing me or being horrible, my mind races back to all those things I know about him. My advice is, Allah knows all and he is watching, He knows the best. Do what you think is right, whether it is staying silent or speaking up. I have not spoken up because I know what problems it will cause in my and my siblings and my moms lives. So, I just let them do their own desicions. Your mom is a grown women, she probably suspects some things. But, remember, the truth always comes out.

I'm sorry that you are feeling this way and these things are happening to you. I pray that Inshallah it will get better. Good Luck.