This is answered in a previous thread

http://www.reddit.com/r/AskHistorians/comments/1frtz1/ive_just_read_that_there_was_no_massacre_of/

1. It happened

2. There's tonnes of evidence that it happened

3. Just because one revisionist crank on the internet has a conspiracy theory is not a reason to doubt the weight of evidence that it did happen

Usually the cranks will claim that 'only 10 people were killed but evil Western media says 1000' that kind of thing, the total denial angle is a new one to me.