someone explain please!

I gave up on getting my ex back because it was hurting me more then anything. And i was writting a bunch of stuff about how i felt on a papper and when the moment came where i wanted to give up i gave that letter to my ex therefor making sure everything i wanted to say was said and my heart was empty! But when i did that it put us in an argument and i wanted to know why would she even argue? Like if you dont love me, it just means you never did (because i believe that when you love its forever you just dont want to be with that person no more) so her and i argued about that and other stuff so i want to know why would an ex argue with her ex after 5 months of the break up? Does she still have feelings?

Ps im still giving up