How to deal with 'cyber bullying'?
Put the person on block
If it becomes a serious problem and they try to stalk you in real life call the police
Don't be a pussy and just sue them if they become that much of an issue or get a restraining order
People like this are usually stupid, they're not intelligent enough to hide their personal information and can often be easily tracked down, see Tommy Robinson getting death threats as a perfect example from some stupid university student who lived with his mom.
As somebody who did actually have to deal with legitimate issues at school where my physical safety was at risk it pisses me off seeing everybody get uppity about a few mean comments online, grow up, cyber bullying isn't real.
Many other fellows will not agree with you including myself