That sounds pretty terrifying,As Divine said Stranger's aren't worth doing that.People online lie all the time.They don't have to be face to face with you so it doesn't matter to them if they never talk to you again.I had many online "Friends" who said I will always be here for you then never even answer my messages.
Hurting yourself is not worth it,especially if you are doing it just to "prove" yourself.
Have you ever considered talking to a counselor about this issue?
In no offense at all,But you don't see to take rejection well,Maybe you could get some help for that?
Be safe & Don't hurt yourself for strangers.The harsh reality,They don't care if you hurt yourself.People today can be very cruel.