<human>: I have been seeing a girl, "Riona", off and on (and I don't mean frivolous, weekly breakups) for about 2 years now. We both have jealousy problems, yet we always make up and get back together. Lately, things have been really awesome, and I have been contemplating moving on to the next level with her. Then five days ago happened. 
You see, Riona is friends with all of my coworkers. Apparently a few of my coworkers told Riona that I had been hooking up with another girl, ehh lets say "Mila", because we had been at a party a few times together and would occasionally hang out after work. This partying and hanging out happened while Riona and I were on a "break." I know, stupid move, but I wasn't really thinking. On one of these drunken nights Mila tried to kiss me, yet I brushed it off and thought nothing of it. Well, Mila decided to tell everybody at work that we had made out. Riona caught wind of this and now completely distrusts me, and I fear I may lose her over some rumors. I did not hook up with anybody, so I did not apologize for that, but I did apologize for hanging out with Mila and talking to her when I really had no business doing that while on a break. This didn't really seem to make her feel any better, and she is still convinced that I cheated on her. Please, reddit, what can I do? I do not want to lose this girl. We spent two wonderful years together and I can't stand for it to end like this.

Provide a brief overview of the text.
<bot>: coworker lied about her and I making out, love of my life heard about it, distrusts me and I might lose her now. What should I do?