So my ex broke up with me 3 months ago and absolutely shattered my heart... after 2 months I tried to contact him and he basically told me (very angrily) to leave him alone as he was trying to move on and that he had nothing to say to me and wanted me out of his life forever etc etc. In fact he was very harsh and cruel about it. Anyway 3 weeks later I get a text from him asking how I am! We have now been texting for a week or so but I don't understand why?
The texts are very sporadic and usually just consist of small talk abd are quite cold.
Sometimes I don't hear from him for a few days.
I don't understand why he suddenly wants to talk? Or what he wants?
I am too worried to ask him up front in case he stops.

In case he stops
You are better off wanting him to stop. After how he treated you when you contacted him I wouldn't give him the time of day. Sounds like whatever his plans between breaking up and him contacting you fell apart. Or he is bored at times so figures you can fill that void while his new girl is away... or something along those lines.