Does this mean all coins will be hacked if we use Telegram's services or provide information to them?
I currently use the fluctuation notification service in the MEW wallet and currently notify when an email arrives. So can they access my wallets and my email data?
You are likely to be hacked if you are signing up with phishing sites. Don't sign up or give information any of your login details to anyone or any website that you are unfamiliar with if they ask for it. And if you receive an email from a stranger and they have given a link for you to click, please don't bear with it and never click it.