I imagine your slip caused his fear that you will not succeed at sobriety to be realized. Scary stuff for him I'm sure. But him allowing this fear to be turned to resentment and leveling that against you was not productive. But neither would your reacting to his reaction with similar resentment... Both behaviors focus on the problems rather than the solutions. Sometimes it seems we can't help our feelings, but we have a choice in what actions we take after processing said feelings.