Cheating help....

So my partner and i have broken up due to mental health issues and we agrees on gettinf back together as soon as we are in a better mental state, however we both agreed on remainimg 100% monogamous to eachother even durimg this seperation, recently we started talking again and my partner told me shes been really sad about us being broken up so shes been hanging out with friends alot amd even been asking her friends relarionship advice, but she told me that she made a friend that happens to be a girl (were a lesbain couple) and she has been tellimg her our problems and askimg for advice, however when i asked to see the conversation (they were messaging) she said no. Now im thinkimg shes been flirtimg with her amd probably cheatimg as well BUT WAIT THERES MORE... i asked her to see the convo and she sais she deleted it. SHe then said i was actimg crazy, and refused to show me the convo, later that day she said, if i truly wanted to see the conversation i should message the girl directly, she said "just message her yourself and she'll show u" on one hand i wanna message her to see the conversarion and make sure there wasnt flirting, but on the other i dont wanna talk to her? What should i do? Message her about it or no