My ex cheated on me

My ex [29 f] was cheating on me [29 M] for the past 6 months. We were in a serious relationship for 6 years. The past year we had some issue related to getting married ( her parents didn't approve of me ) I thought she would stick with me and we could fight it out. But I recently found out that she had moved on with another guy and was in a relationship with him..while she was still with me..she started acting distant from the past 3 months and I gave her space. But then one not so fine day I see her roaming around with the new guy. I confronted her saw the texts...that she was clearly lying to him about me, our relationship. He now thinks that she had moved on and she was meeting me just to help me move on. She did try to break up with me a couple of times in the three months but I literally begged her to be with me. We used to go out for coffee and food. It wasnt how we were but I thought we were still together...so I want to know if I should let her current boyfriend know the truth about us and then let him decide if she wants to stay with her.

PS - Not entirely sure if I'm doing this to get revenge or to help the guy out..

I do still miss her for some crazy reason.

Help me out people 😭😭😭