Are you asking if you should reply to simple texts and emails from your XH?
If so, I have never felt comfortable ignoring things. I think it is just plain rude. You can answer in a way in which you are not investing too much of yourself. As you can see from my little text of last night, I let it go quickly. Only you can let yourself get sucked in.
And, please don't point out how ridiculous it is of me to be giving the very advice I rarely follow!!!! That is just plain rude, too.