Why does she play mind games?

me n my ex of 5yrs been broke up for 9months now....we had a few months were there was no contact. then out of the blue i get a letter saying that she wants to be friends and deep down she still loves me...well we talked for like 3 days and then all of a sudden she changes her num wont respond to any emails. i fell like a idiot for even calling her in the first place because she hurt me really bad at the end of the relationship...i tried to forgive her so i can move on but its been one of the hardest things i ever had to do...im 37 and experienced my first heart break...neway come to find out my ex is bi-polar so that explains some of the bizarre behaviors i experienced with her. i just want to know why the hell would she contact me after so long to just act like i dont exist once again..what is wrong with her....better yet what the hell is wrong with me