My [33F] husband [38M] has been cheating on me while the kids [5F, 2M] were in the house

I just uncovered all of this a few hours ago and I am still a wreck so my apologies if this sounds incoherent.
We have 2 small children together, 8 years of marriage, a house and a dog. The perfect life until today. We are both working full time and I am also taking some online courses for my Masters degree. Due to my job, I am taking business trips every month for 2-3 days at a time. It was my homework for the Masters that caused me to use my husband?s computer today since my laptop was at work. Some might say that I invaded his privacy and I should?ve asked for permission but he was at work and I honestly didn?t think he?d be upset if I did my homework on his PC. I go into his office, sit down, and start doing my thing. The computer is one of those Apple desktops and it seems like his phone was connected to it still because I kept seeing notifications from iMessages. Curiosity got the best of me since they were so many and interfering with my concentration, so I opened the app. My world shattered in seconds. As I was reading through the conversation, they were chatting still. It was clear that the person was a female and that they were very very comfortable with each other.
I don?t have the patience to write out everything I read in there but I?ll summarize it. I have found out that they started this at least 1.5 years ago. They have been exchanging explicit pictures, sometimes taken within a few feet of me or our children. He met her while in the park with our kids. She frequently visited our home while I was on my business trips and our children were asleep. Pardon my language but my husband ****ed this girl in our house, on our bed, with our kids sleeping on the other side of the wall. This woman is young, maybe 25 years old. It comes as no surprise though since my husband keeps very fit and is quite handsome and charming. He has a folder in the computer with pictures and videos they took in our bedroom, living room and bathroom.
I left the house and I?m currently at my sister?s. I don?t know what to do and I haven?t made a decision yet but I cannot sleep with him in that bed anymore. The kids are at home. I told him it?s an impromptu business trip so I wouldn?t be surprised if he invited that girl over. I?m at a loss. What do I do?
TL;DR: my husband cheated. Brought his girlfriend over into our house while the kids were at home


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