Indecisive partner...now I have lack of trust

My partner and I have been having some issues. Been going on for the last 2 years out of our six year marriage. We been fighting alot and saying alot of hurtful things to each other. She has decided that she wanted a divorce and now she's not sure. I know I've been going to see a therapist for my issues and things between us has gotten better and we done things like couples normally do.

But here lies the issue. I did find out that she's been talking to somebody else and she claimed that he was just a friend and someone to vent to. But normally I have to shut off her phone when I get up in the morning before I leave for work and saw the messages and scrolled through them and noted alot of red flags. The guys name was Frank and now it's sweat heart Italian in her phone in Italian with hearts in the name. The theme background got changed to love and there has been a lot of messages that really give away that there is something more then just friends. She has told me she did begin to have feelings for him and lost feelings for me at the start of the year in 2021. But to her it was hero sindrome because he was there someone to vent to. And she claims they stopped talking but now she seems to be pulling away again. Still leaving me with no definite awnser if she wants to get back together or just continue with the divorce.

So now that a couple weeks past by I still have a gut feeling that she did cheat and that this other guy got her attention and that I'm just being played. She did say to me that they where just friends and it bothered me and then after finding out about there messages who know exactly the extent that it ended up to. Because she's lied about it before and I've lost most of my trust with her now and don't know how to go about talking with her bout it or if I should just say time to end it and continue the papers for divorce? I need some guidance on what I should do cause idk anymore. I love her but yet I can't get the gut feeling out of my mind that there was something that did happened.