Sassy,
I would not describe your response as heartless and cold, rather heartfull and angry. Feelings aren’t something that are right or wrong, they are just feelings. We have them! That’s enough!
If you want to do something else with your time, you could look into the causes of anger and try to dissolve them. At this point, because it is just ruminating in the past, perhaps letting all of it go would be simple. Excuse or passed out, either way its OK. Angry or compassionate, either way its OK. With odd phone karma in the union, it is perfectly normal to become disturbed by lack of follow through with plans.
With warmth,
Matt