<human>: Give me a shortened version of the text

We dated for 2 years, from a bit before university until now. So, we've made all our friends together, and we were each others' best friends. But, as happens, we grew and I changed and we couldn't reconcile our differences, though we tried for months. We eventually broke up peacefully. Aimed to remain good friends. We used to be everything to each other, after all.

Some time later, I messed up and told him that I kissed someone right before we broke up. (Cheated on him.) My ex also knows I like this new person, and still want to pursue him romantically. Understandably, my ex can't stand him (even though he did nothing except mutually kiss me). He told me I'll have to choose between the two of them by the end of the next couple of weeks. I know I'm a terrible person for messing up, and I should choose friendship, but at the same time, is it really friendship? I'm also happier with the new guy than with him...
<bot>: Do I choose new guy I might have cheated on my ex with and risk losing my ex's - my best friend's - friendship?