J'essaierais de comprendre juste ce qu'est arrivé avant que je me sois sois fâché avec lui/elle. Dans l'anglais: I would try to understand just what happened before I got anry with him/her.

In fact this won't be simple, but what I will do is to forget about him/her because he/she doesn't deserve my friendship. (I must be sure of his/her betrayal)