So after speaking with my IC, I decided to confront my wife about the fire/oven mitt while sexting at my house incident from last Friday.
I think it went well. I calmly asked if she is using the computer, she said yes. And then I explained that she had left the window open on Friday, and I had seen the sexting that was going on at the time of the fire. I kept my focus and concern completely on her being safe at the house with the kids. I realize I can't control what she does at the house. I reiterated that I would prefer she did not sext from the house or around the kids. However, I realize that if she does I'm powerless.
Overall, she was amazed that I had known about this for several days, and didn't mention it previously. I'm happy with how I handled it. Calmly, strongly, and decisively focused on the safety of the kids
No yelling and no screaming, and it was discussed, she apologized and I have moved on. Hopefully she doesn't do this again