I think you have grounds to do something. If that had been child protective services that walked in the door last night and not you, you would have lost your child, at least temporarily. She was clearly put at risk and the whole light bulb thing is just strange but also puts a child at risk, as you found out last night when you were trying to help her. I think it's good you got there when you did and yes, I'd be furious if I was you. (I used to investigate child abuse allegations).
I would start looking at what Utah's courts are like. Do you a lot of people go through the system without attorneys? Most family court systems would have some provisions for that. It makes it more official because if you really start fighting and things get ugly, you don't have anything to back you up legally. That being said, since there isn't anything legal, you can make the choice to withhold access and put it on her to take you to court. I'd be sure to be writing down all of this somewhere and date it too.
The other thing I'd suggest to you is to keep yourself in check when it comes to the other man, in fact, I wouldn't even bring him up if you end up in a court like situation. Places like here....vent away. I wouldn't want my kid around him either but threatening him, if you do end up in court, will work against you. Keep it clean, no matter how much it kills you. Sadly, I've seen many good dad's get screwed in court if the woman decides to go on a witch hunt. So don't give her any ammunition. She's clearly making very poor decisions and you just have find the best strategy to protect your daughter and yourself.