if its annoying then dont text him back. simple.
but obvisouly you want to text him back, thats why you put it on this forum, if you text him back it doesnt mean that you want him back if thats what your scared of.
if you want to sms him then stop thinking about it, and sms him. why put yourself through all the stress of thinking if you should or not? just go with gut instinct.
some poeple might say 'remember why you broke with him in the first place', this is one of the most pathetic reasons (if he cheated on you thats a different story, i think that if someone cheats there is a very high likehood of them cheating again) not to sms him. people CAN change and relationships DO take work, thats going to be the case whoever you are with.