My (32M) girlfriend (28F) says she never cheated.

I (32M) and my now ex as of this week (28f) had been together for 6 years and have a 2 year old daughter. In the beginning of April a coworker and " good friend" of hers needed a place to stay since his room mate was leaving the state. She offered him the extra bedroom we have for next to nothing since it was only for what was supposed to be a few weeks. Fast fwd 5 weeks on Sunday, I go to bed around 8pm with our daughter as she stays in the first floor with her "friend" drinking. I'm texting her every couple hours at first asking her to go to bed and she brushes it off saying " I will in 30 min". Fast fwd to 1 AM, I looked at the indoor cameras in the house and noticed they are all disconnected. Which is odd as we have several dogs and online in a neighborhood where it can get sketchy. I go downstairs and all the lights are off and they are in the kitchen with there hands wrapped around each other and what looked to me like they just got done kissing, but I didn't see the kissing itself. She noticed me and pushed him off her. From there I kicked him out the house and we had the biggest argument in our 6 years where she broke up with me on the spot saying she doesn't love me anymore. However, we are now staying cordial for our daughter but after discussing what happened she states that it's not cheating and she never had. She told our friends and family that she broke up with after she fell out of love but refused to tell anyone what really happened. I'm asking now if it's cheating because family and friends are asking me how am I doing and asking what happened as we were that perfect couple. Should I say the truth and just tell them she cheated?