Struggling with my breakup.

Hi guys,

My partner broke up with me 12 days ago following a year long relationship that was happy and healthy for the most part. Of course we had our difficulties that we were working through with professional help.

In the early stages while we were still dating, I went on a few dates with another girl, after my ex said that I should continue to see other people. We were both open about who we were seeing at the time, so my partner was aware of this person. Fast forward 2 months in, we had spoken about being exclusive and agreed that we would both cut ties with the other people we were seeing. I continued to exchange texts with this person upto a few weeks after we had made that agreement as I was worried about hurting the other person's feelings. Eventually I did sever all ties and never looked back. Since then (8 months ago) I've been completely committed to my relationship with my now ex.

Anyway, 12 days ago after a night out drinking on my birthday, my ex went through my phone and discovered the messages between myself and the girl, and broke up with me, saying that I'd cheated and tried to hide it.

I completely understand why she was hurt and felt betrayed. We've never checked through eachothers phones before but I gave her the password to my phone as I never felt like I had anything to hide. After I severed ties with the other person I didn't think to delete the messages as it was something I'd left well in the past.

(Continued in comments)..