Harness the emotions you are feeling about his disbelief and use it to fuel your sobriety.
I am not sure if this is your first or hundred and first time at sobriety. If the later, it is understandable. Unless he is an alcoholic than he cannot understand and never will. You are not lying, you believe to your core that you will not relapse. We all do when we quit. The disease has a lot of power even to make us do things we say we won't.
I would give it some time - 19 days is great and you should be proud. Keep driving forward.
He may also have some co-dependance issues too (not knowing your situation) so depending upon how long its been going on he could even want you to relapse - again, I am not sure of the situation but have often seen this is spouses - one may feed off the other being worse than them.
Good, luck focus on you and your sobriety and work your network when you need help.