Faithful in A life unfulfilled

On Aug 19 my mother and I talked about her new fling. She’s married to an asswhole and has another man in mexico whom has never had any physical contact since the late 90s. When we stayed at the friends about 2 entries ago, He gave her his number and to my luck she’s been talking to him. My mom is beautiful and youthful but not really faithful to her husband. Today on Aug 20 she went to see him about 2 hours ago. She left us in a motel that was horrendous. It smelled like cigarettes and brain matter. The sheets had a blood stain along with a nasty hair infested bed. She paid 60 for that which I stayed in there for about 2 hours. I wiped it clean for my siblings. I also tracked my mother the whole time and it showed her go in and out of his house about 30 minutes apart. She had sex with him… Her hair was messed up and her dress was wrinkly. She cried on our way home because she felt bad and she’s never done this before.
I told her I’d never judge her but she had sex and she refused to take plan b because she wore a condom. I didn’t know how to look at her. It’s difficult to see her the same. She had an affair. I know I’m being difficult but I feel that it was infair to me. Yes she bought us food but at what cost?!! I hope she blocks him on social media because we’d have to starve again if we move out. I don’t know how to think or how to behave. Should I let her and watch my siblings so she can do it again or should I not let her? Lord I pray for your forgiveness but I don’t regret helping her. I just wish I could escape .