Living with my ex, she slept with someone already and hid it from me.

Me and my ex, broke it off in January. At first it seems like it was getting better , w the possibility of mending it. In Feb, she went back to her home country for a few days to visit.

I have now just realized that she was fucking a "friend" all that time back. And also fking me at the same time.

I feel upset that I didn't know about this. But conflicted that technically we are broken up already, I perhaps shouldn't feel this way.

After since coming back in February, she said she needs time to think about us. But she has been sexting and calling him. All the whole timee and her have been still physically involved time to time. It's confusing.

Now she knows I found out and intends to ghost the guy.

Someone give me solid advice on what to do Should I even be feeling upset ?