Need girl advice....

Sia • Lmao for ppl that think this is a legit account it`s not. I made this account under my sister`s identity to show you female`s how you act to each other and yourselves don`t take my "issues" seriously.
Okay, so my ex and I planned to get back together but I found out that he had a gf on the side...I feel soo horrible because even though I had no clue I was hitting on some other girls' bf.. Also when I told him off, he ended up advertising her on his profile. He didn't seem to care about her until I told him I was over it all..I'm soo confused and need some serious advice. Please comment.