1) Even if English is not your native language, you still should be able to spell.
What does being able to spell mean?
Would you expect a 6 year old person from USA to be able to spell?
Would you expect a 20 year old person who never had any education to be able to spell?
...It really boils down to, not everyone have the same opportunities as you do to learn English, and it is good to correct people so you help them learn imo, but responding to them in a negative way is completely unfair.