Sorry to hear your son got neonatal lupus. But, as a mother, we all do our best for our bb, so please don't cry and blame yourself for fault, it isn't good to your body and your son can sense your sadness too.
Neonatal lupus is not permanent and SLE (systemic lupus erythematosus), so he will recover when your antibodies start disappearing from him(roughly around 6 months of age). As long as the disease doesn't affect his heart, liver or blood, it's all good! Knock on wood, if there is anything happened to him(hope not), it is also treatable with nowaday medical technology, so please don't worry too much ah.
One thing you have to be cautious, those rashes are sun light sensitive, so please avoid the exposure of sunlight.
There are lots of medical websites containing info about neonatal lupus. You can search it online while you have time.