I can tell you a couple of things. Easy to live on that sort of money if you don't go daft and out boozing every night.
Bar family commitments my personal spend is less than Rp600,000/month.
That allows me to eat at restaurants every day, wander around on my motorbike and do pretty much whatever takes my fancy.
Most here in the sticks are living on Rp400,000 a month but are a bit skint.
The second thing is that they are ripping you off. Salary is way too low.
Ask the English teachers on here what they get but I've been offered (and refused) a lot more.
Added - the last I was offered was 2 days/week at 500,000 per visit.