My question involves labor and employment law for the state of: Colorado

I'm a restaurant manager. A few days ago, my phone feel from my pocket in the parking lot when leaving for the day. I didn't realize it until I got home. It took me about an hour and a half to get beck to retrieve the phone. In that time, I had 2 missed calls from the store phone. I didn't realize until the next day that the notifications were dismissed. An employee told me the next shift that the general manager went through the phone and read text messages and looked at photos. I watched the security cameras and verified that this happened. She called the phone to make sure it was mine and then her and a subordinate of mine read through it for the following 45 mins in the office of the restaurant.

It is obvious from the messages and photos that I am sleeping with a co-worker (that doesn't report to me, and is at the same level (RM)) and I am fraternizing with one other staff member (that does report to me). As well as a few other message threads from 2 others that she is angry about. She has stated to the waitress that told me that she "will need two new managers and so she needs her to step up". As well as that she intends to terminate all the rest of the people mentioned. I have the footage of her doing so as well.

My questions is, can she use this information against me and the rest. Is it a legal form of investigation to go through phones owned by staff members? if necessary, I can provide the investigation and phone policies from the emp handbook.

The GM has been off since this incident and returns to work today. I start a week of vacation today. So we wont see each other for 9 days. Should I consult a lawyer in the process?

I would like to have this person (General manager) terminated if possible and protect those that communicated with me through this phone. The embarrassment that my co-workers and myself experiencing is immense.

Thank you in advance and I hope I provided enough information.