We broke it off, and she jus texted me out of nowhere?

me and my ex were dating for like 3 months. long story short, she dumped me and told me she couldn't handle a bf right now. lame excuse, i found out 2 days later shes goin out with her "best guy friend" they dated before! made me really pissed. the fact that she straight up lied to me and no appoligie for lying at all. i could never trust her as a friend at all. shes done alot of other things too. she texted me out of no where ( about a month or so later after we broke up i guess) i haven't really said a word to her, called her, texted her. anything. i have very little respect for someone who treated me like crap. she texed me today jus trying to start a conversation. i never replied. i wanted to talk to her too see what the hell was goin on in her head to do what she did tho. am i in the wrong at all? i really dont feel like i need to be friends with her at all. am i too harsh? i want her to know she screwed up and she missed out on a great guy...