My problem is I don't answer in my head. I think to myself, I need to craft a reply but I need time to do that, but then I don't want to make the time to do it, and then I just don't do it or I wait until way later when I crack and think "well I gotta say something" and send a half-assed reply just to put it out of mind.

Answering texts is virtually no different to doing homework in my brain.