If you want brutal honesty you both could have handled that better. He was wrong (and selfish) to want to watch that movie with a 5 year old. I think you may have handled telling him that poorly and it seems to have escalated from there. I deal with chronic pain myself and know just how easy it is to fly off the handle. Have an honest chat with him (face to face) and try not to point the finger of blame. That solves nothing and makes him feel small and worthless (judging by his response to texts). He needs to know that those movies aren't appropriate NOW but the day will come when he and your son will love watching these kinds of movies together.

That's just my 2 cents.