I can't stress enough what MrPresident said:
Ignore them. If you want to report them to Steam or others, go ahead. Just don't interact with them. Don't give any response. Most internet trolls thrive off attention. They all have limited resources, so if they don't think they're making an impact on you they'll eventually get bored and move on.
A few precautions you can take:
Change all your passwords, and make sure they're secure. Don't reuse any passwords between sites, especially not your Steam password because if they try to break into any of your accounts it's going to be that.
If you can, turn on two factor authentication for your Steam account and any other important accounts (email, bank, paypal, etc.).
They probably won't be able to find anything other than your Steam account, and unless your password is insecure (along the lines of 12345 - check
https://howsecureismypassword.net/) they won't be able to break into that. Your site is on CloudFlare, so not too much damage can be done there. But of course, better safe then sorry.
It's too bad you're experiencing this, and it's sad that some people spend their time to ruin others', but that's the internet for you. Good luck.
